I just did a full achievement run of PvZ1 prior to playing PvZ2, and they're not really comparable. The progression in PvZ1 is linear and skill based, with a small set of unlockable plants to augment the post-mainline content. In PvZ2 the progression is non-linear and grind or pay based, and that is primarily to drive the IAP mechanics. Eg if it's not clear to you what order to tackle stars, etc., you're more likely to spend coins on powers, or new plants, etc., in an attempt to get through content that would otherwise require high level play (or the cheese outlined above).
So now you're playing a metagame--what order do I play the stars in order to avoid the IAP walls, or how far can I get without paying anything. I hate that experience, and if I could have just given them $15 to play them go sans IAP I would have. But a key question to ask yourself is, would the mechanics and progression have been designed differently if there was no IAP? And the answer is of course. Because you can't do successful IAP without that inducement in the mechanics themselves. So it's lose/lose.
100% agree. PvZ2 is the new Diablo 3.