I like this one so far... addition of pause function + duplicate gem will make the late game much better instead of being a click fest.
On the other hand (and I may be wrong) it seems like supergemming is out, which is interesting. You can beef up the specials but not fire rate. Also the wave options menu is definitely bugged - often can't select one or more of the options.
I don't mind the premium content... this game has a lot to it and is well done, and $5 isn't bad AND it's optional :)