Ulpan Bayit was one of the best language learning experiences I’ve had. It’s hard to overstate how much I learned and how much fun the learning experience was. Yaron and his crew are are a bunch of very fun, very talented Hebrew teachers, not to mention very friendly people. If you’re planning on being in Tel Aviv for an extended period of time — regardless of your Hebrew level — you should check out some classes, because you will learn a lot very quickly.
As a few other reviewers have said, the relationship in the classroom is less teacher/student than a friendship in which one of the friends is teaching the other Hebrew. It’s a very social learning experience, and during class and between breaks you will meet a lot of other people who are trying to get their bearings in Tel Aviv.
Oh, and if you’re deciding between ulpan in Jerusalem or ulpan in Tel Aviv (or in any other city), pick Tel Aviv, and then thank me later.