I've had a truly excellent and inspiring time at ActiLingua this year and I'm happy to recommend this to anyone looking for a chance to learn some good quality German at the spot. The environment is very friendly, the teachers are eager to answer every question that pops up and show as much support as needed. Though situated in Austria, there are also some teachers from Germany. The course itself is pretty versatile - the standard version consists of 1.5 h of grammar and 1.5 h of speaking/listening exercises, both made very well. Additionally, there's an option of an intensive course, which is a mixture of grammar/vocabulary/speaking, and even individual lessons. One thing that has to be taken into account is that although Linguatrip site enables one to choose the afternoon or morning classes, the true time is set on the day of your arrival - everything needs to be organized accordingly to the number of participants this week and their level. So it may happen that even though you booked the morning course, you'll end up studying in the afternoon. However, I think it's worth it. Additionally, there's an option of borrowing a dictionary from the school for the time of your stay for refundable 10 euros - they're pretty well supplied, so chances are they have your language!
The school provides an opportunity to go out on some kind of evening activity or even a half or whole day excursions fairly often. I personally did not opt for one, but it's good to mention there are many free or pretty cheap occasions to do some group activity outside a classroom.
About the accommodation, the shared apartments at ActiLingua Residence are also quite nice and rather affordable, compared to other possibilities. As always, the cleanliness could be improved, but it was in no way unacceptable. It, of course, all depends on your roommates - some love to clean immediately after themselves, some leave the dishes to "breathe in the sink" for a while :). I do recommend getting a single room, although there's a little gamble involved: while there are plenty of spacious single rooms, there are a couple of livable, but smaller ones, too, so it's a little up to your luck.
Overall, if you want to start speaking more German or feel like a foreign journey is a right step towards your language goal, I highly recommend this school. Not only will you have a chance to improve, but also see the beautiful city of Vienna (do you know many museums are free if you're under 19 y.o.?). Probably the best time to go is somewhere between spring to early summer, as during the months of July and August there are a lot of teenage camps at the school and most courses are afternoon ones. Also, it's worth knowing that many people come there for a little longer. From my experience, I can tell that if I were to come back, I'd go for at least 3 weeks (actually I think of coming back next year for a full month). Worth the time and money!