I attended the Middlebury Language Schools this summer for Russian. The program at my school required 12 credits of a foreign language which would have been 2 years of 1 class per semester, but I decided that I didn't have time for that and tried to find a faster and more efficient way to receive the credit. My school didn't want to award me the credits even if I attained a certain proficiency by myself because, surprise, they want your money. I continued to look, and I found Middlebury which awards 12 credits for only 2 months of in-residence work. Jackpot! However, to receive the credit I had a lot of paperwork to go through which included what is known as a consortium agreement which allows you to apply for aid through your home institution because the Language Schools are non-degree granting so you can not receive federal aid through them. If you're lucky and apply within the first week or two of the aid application opening up, you can receive up to half of the tuition in aid (it goes fast) which is important because the school is very expensive. Fortunately for this site, I met quite a few that were either sent by their command, workplace, or using the GI Bill. For any further work, your school's financial aid office or registrar can help with that because I only know what I went through. They also have some fellowships available, but these are incredibly competitive because there are some high level students attending these programs. Seriously, I felt like a fish out of water relative to some of these peoples' "pedigrees" or accomplishments.
For each school, there are many levels in each language from "can't pronounce a word" to graduate level study. If you already have some experience with your language, they will put you through a written test and an oral proficiency interview to determine your level according to the ACTFL rather than the ILR. A comparison is available here. In general, people with 1 year of study in college were put in level 3 and scored roughly intermediate low, or 1. If you score advanced/2 or above, you can be placed in the levels where they actually study politics, culture, etymology, etc., rather than grammar. All other below levels focus heavily on grammar and actual usage. All levels learn a significant amount of vocabulary which gets more and more the higher level you are.
Now to the program and my experience which is purely from Level 1 of the Russian program and conversations with students in other levels. First off, and likely most important, you are required to participate in the Language Pledge which states that you will speak only your target language for the duration of the course under threat of expulsion with no refund. This includes texting, internet usage, and any manner of communication. No reading the news or anything unless it is in your target language. you can go in to town, but you are still expected to use Russian, and the locals are used to this. This is highly useful and necessary if you wish to make any kind of significant progress in only 2 months time. In reality however, the majority of people make a valiant effort for the first 3 weeks until they have felt each other out and realized that they can get away with spurts of English. As time goes on, you grow incredibly tired of having purely surface level conversations with people that you spend nearly your entire day around. Everyone gets more comfortable with English in small isolated groups so that they can actually get to know each other, and during finals week, you pretty speak as much English as Russian.
The program is very academic as it must be. They award credit for this even if that is not your reason for attending. Class time is 4 hours a day Monday-Thursday followed by test day on Friday consisting of vocab tests, written tests, and oral tests. They also offer 1 hour of office hours after dinner. To finish out the day, you will be assigned a decent amount of homework which wouldn't take that long except you have to write in Russian cursive which is a pain in the ass at least for me because I accidentally write in Russlish because some of the damn letters look the same, but make different sounds. Yes, I'm still salty. Now depending on how quick you pick this stuff up, it could take you 1-2 hrs or it could take you 4hrs. It just depends on you. Finally, on the weekends you will be typically be assigned an essay, and some other stuff that is level dependent. One level that I know of had to memorize poems. It just depends.
In class, all levels focus heavily on writing and reading. There are plenty of exercises in speaking during class and you practice your listening pretty much all the time, but the majority of your class time will be spent learning new grammatical constructions and practicing them by speaking and writing. The homework is all written with a little bit of listening thrown in. The program is pretty much like everything else. You get out what you put in, and you can practice your new skills as little or as often you like with however many people you like because you all eat together and attend various clubs or sports together. The program environment is incredibly social and heavily encourages it, but again, if you hate people or get tired of the language sometimes, you can retreat to your room. None of the extracurriculars are mandatory. Just highly encouraged and sometimes fun. They offer movies and lectures all the time. They have parties with cash bars, and even lake trips. The city is great and there is a great 18-mile trail around the city that is great for training if you're a wannabe like me.
My critique: Everyone's main complaint with the program (if they had one) was that it is very very academic. Every course was required to have a textbook or two, and no matter how little you may use the textbook (we lived out of it), it was still too academic. That could be personal preference, but I could give a damn about writing the language. Everyone believed that they needed more supervised speaking practice, and phonetics practice which brings me to another weakness. Your peers aren't native speakers either so they will understand you even if your pronunciation is god-awful. That means that you are practicing poor mechanics in both speaking and listening. Also, the program is pretty fast paced so the professors don't have time to worry about your pronunciation until you get it right. The groups are small, but they still have other material that they need to teach, and they can't fix everyone individually. That said, the professors are freaking awesome especially in the 1st level. They want to be there and will work their tails off to help you if you show that you want to learn. That's pretty much it. Everyone complains about how much writing they do compared to supervised speaking, but it's an academic program and simply can't be perfect. However, their methods are hard to argue against because you are still practicing your understanding regardless of medium.
At the end, you will take both a written exam (just write essays for 2 hours), and an unofficial OPI so that you can see your tangible results from beginning to end. Most people go up 1 or 2 levels. 3 isn't common but not unheard of. I participated in some sort of language research so I took official ACTFL testing, and recieved intermediate low, intermediate low, intermediate mid in listening, reading, and speaking, respectively. According to the comparison that puts me at 1/1/1 across the board for DLPT standards. Most people in Level 1 that did the unofficial testing received similar results. That means they went from absolute zero to intermediate in only 2 months time. Those that scored intermediate low on entry scored in a range from intermediate high to advanced, or from 1 to 1+ or 2. I've heard that jump from intermediate to advanced is real tough so that's pretty good.
All in all it's a great program that I highly recommend especially if you are using someone else's money. It will save you a whole lot of time in school, very likely make you a much better speaker than just college courses could, and give you a very solid base to continue study on your own or a great opportunity to level up your skills. Also, there were a lot of on-campus meetings with many government agencies, and you will forever have access to the school's career center/network if that interests you.
P.S. If you aren't using other people's money, then there are other language immersion programs that you might be able to get credit for that cost way less. Ask about the paperwork I mentioned or speak to your school to see if you can get credit.