I think the biggest problem with Tower (and I'd argue also its biggest strength) is the lack of focus. I mean, if you're like me and you love to jump from minigame to minigame, from activity to activity, condo to condo all in the same game with the overlaying systems on top while still earning currency, items and achievements, you'll (perhaps eventually) love TU. But if you like a single part of Tower? Then you'll be probably able to find a different game that does that aspect better, that does it more. There are exceptions, of course, but even the more unique parts will suffer from lack of updates dedicated to them.
Then again, that allows the devs to create a truly diverse experience that people like me enjoy so much. (The question is whether to focus on developing gameplay that can be found elsewhere) Plus there's the community aspect, of course.