There are a few things about S2 that I think are great; the world selection (and that theyre separated out individually), the online "battles" (although Im still not sure how that really works, but its interesting), the costumes.
But, it feels like every possible freemium mechanic has been crammed into the game. Between the energy system, the earnings rate & IAP costs of stars/diamonds compared to store/revive costs, the costs of failing a level (you lose badges, the tick of energy you spent engaging the level, the level resets to wave 1, and it apparently re-locks other zones that were previously open ~ which (sometimes?) cost diamonds to re-open)... combined with the game play itself (and that it can be very time-sensitive, yet is not totally reliable about recognizing/accepting a symbol) ~ altogether, the mechanics just feel overly harshly punitive. Im actually -less- inclined to make any purchases because it doesnt seem like its worth it and I believe Ill just end up feeling like I wasted money.
Im not totally positive if the areas are -supposed- to re-lock; the game seems to be slightly confused about which zone is which; for example, when I select the Graveyard (which was open for play initially), it now is locked to me, does not offer the option of paying to unlock it, and tells me "You havent unlocked Hills yet."
As some other reviews mentioned...
• The first time I installed, I got "stuck" in the tutorial; at the point where I was supposed to make a combo, it simply stopped recognizing symbols and I was unable to continue; the pause button and ability to quit the level still worked, but doing so apparently counted as a loss/death.
• I deleted and reinstalled; after a couple attempts I was able to finish the tutorial, but the game kept finding the other iCloud save(s?) and asking me about them.
• In the Forest; once I had progressed far enough for Mia (the "flying" Crawler) to appear... yeah, it shows up in the earlier waves now and is just making life miserable. The game seems especially prone to not-recognizing that particular symbol during waves and the speed and movement paths of the critter tend to leave no room for error (if you have time to do anything at all... often as not it makes for a situation of insta-fail, and considering what happens when you fail a level... its just frustrating). Im halfway tempted to re-install again and avoid progressing that far just to get rid of the thing.
• The story line isnt terribly thoroughly explained, and while the tutorial (when you can complete it, anyways) covers some of the basics, I think Id feel a little lost if I hadnt played the first game and seen most of the general game mechanics elsewhere. And I still have questions ~ like not being totally sure how the online teams/battles work and what exactly counts as participation, why zones are re-locking and if/how that can be avoided, Im not sure what XP and leveling up does for you or what the benefits to the ranks (Newbie, Sergeant, etc) are (at some point I went from 5 energy to 10, but Im not sure why/how/where-that-came-from), if theres any significance to the league/global/team ranks, Ive unlocked the bonus level a couple times but am not sure -how- I got there (all I know is that it doesnt automatically happen each time you defeat a boss the way it does in the first game).
Im still playing, for now, but am not sure how long the game will hold my interest as it is. Hoping to see some tuning/adjustments /changes with the mechanics to make the game a little more forgiving and less pointlessly-frustrating.