Welcome to Pprune.
I went to OBA to do my JAA PPL about 14 months ago. I enjoyed it. I spent no more money than they advertised. The accomodation is fine for what you need. (About a 20 minute walk from the airport at the most.) I scheduled four weeks to make sure I would get everything done, but I could have been finished after 15 days if the weather has been better. As it was I finished in 20; one day less than three weeks. And I did all the exams while I was there (I did study a lot before I went though)
Of course, you will find others who had a different experience than me. But all I can tell you about is my experience...
I would recommend that you be prepared to work hard, be there and ready when you're scheduled to fly. And don't be a someone who complains about stupid things. (Legitimate complaints are a different matter). Before you go read all the procedures, about getting your visa, thoroughly. It is a complicated procedure, but OBA have it worked out properly. If something goes wrong it'll be because you didn't follow the instructions correctly.
Anyway, wilkommen to the world of flying and enjoy...
Tschüss
Oh, and if you written english is anything to go by, your english is fine. When I was there about half of the students were from non english speaking european countries. I don't think any of them had much language related problems.