I'm not much of a cheesecake person but I really enjoy Uncle Tetsu's. Personally I prefer the lighter taste and feel of Japanese cheesecake vs the heavier, New York style one. The cake is fluffy and falls apart in your mouth upon first forkful - it's very delicate. The sugar also feels lighter and not as dense.
My mom likes to grab one (or 3) whenever she comes downtown. Although there's a reputation for long lines and wait times, she always comes during off-peak hours to purchase them - there isn't much of a line so it's in and out.
I've noticed some less-than-favourable reviews, but I would attribute that to the overwhelming hype surrounding it. Unsurprisingly, when you have high hopes for food (and in the case of Uncle Tetsu's, wait in long lines), it's easy for your expectations to fall short.
Bottom line: the cheesecake is really delicious but don't expect it to be life-changing.