One thing NOT mentioned is the "Pay or grind (and grind, and grind)" monetization model. After you defeat the first world, you need 15 stars OR $5 to get to the second world, with those 15 stars requiring defeating another 12-13 challenge levels. After the second world, you need 30, yet only have 2! at that point.
Unlocking a lot of the plants/bonuses and puzzle levels requires collecting randomly dropping keys OR paying $2.
There are also several plants and bonuses that can ONLY be bought with money, and money can be used to buy in-level powerups which are otherwise exceedingly expensive.
Its not as bad as some "free" games which hide a transition from 'skill' to 'pay to win', but it is still quite obnoxious.
As a consequence, while I would have paid the $10 I spent on the original PVZ on iPad, the insane nickle-and-diming means that I have a choice: Spend a fortune, or grind, or just give up.
And it also makes me recommend the WOPR rule: "The best move is not to play". Don't install PVZ2.