They're both great, you can't lose either way.
TSPP: Long games, but so much depth that you're constantly uncovering new and exciting things to do. Great layout, fun to shoot. Whitestar sound quality is a turnoff to some...but if you can get past that, it is a fun and robust sound package.
IM: Short games, almost no depth or real modes...but it does have some stacking nuance - and a super addictive quality. You want to keep pressing start and going again. If you have a good game, you could get to the wizard mode on one ball...but that's a rare occurrence, so when it happens, it feels really great! Awesome sound quality and music. Hooked to a subwoofer it will rock your house.