I've had the PvZ app on my iPhone for a couple of months now, and I gotta say its one of the best game apps that I have for my phone and certainly worth the $3 I paid for it. I've known about the game for a long time now, as it has been in the top 10 iPhone app charts for months. For the longest time though, I refused to even give the game a chance because I thought the concept was stupid. One demo of it at the Apple Store later, I was hooked.
The thing I like most about the game is that its not really something that I go out of my way to play. Instead, its something to take up any extra time that I may have; its a gap filler. Its perfect for making bus rides more bearable or lectures less dry. My only real issue with the game is that there isn't enough variety between levels to keep it feeling fresh. Sure they introduce new zombies and you get new plants, but once you get a winning formula down, each level just kinda feels the same. But like I said, I use it mostly as a time filler every once and a while, so I don't mind the repetition.
Too bad I can't play it during my presentation tomorrow to make that go by faster... =/