After having beta tested Rift since about Beta 3 or 4, the game grew on me. Its smooth and its fun to play. If I had the chance I would definitely like to play it now that its out.
However I did have a few things I didn't like as much about it, which is given. One big thing was how similar to WoW it felt. The UI, combat, classes, crafting, pvp, and pve all feel very very similar to WoW. And while I do enjoy stuff to be the same, sometimes you just want something different.
Being so similar to a very successful MMO can be a good thing. You can attract the players who enjoyed WoW for example, but they got tired of the content getting repeated and brought back. So stepping from WoW to Rift can be as easy as switching lanes on the highway.
Oh and have a flashy intro video for Rift. =)