Five stars. Simple, yet challenging, but no so hard that you want to scream and give up and opt for the walk-through. I think this was the first puzzle game that I didn't use the walk-through. Great game, hope to see a sequel.
also, just wanted to ask, how do you lose stars? Like, only get 1 or 2 instead of 3? Because I've been getting three stars all rounds (on the third map now) and i've been hit and had units die as well, so I don't know.
IF you miss an achievement, take screen shots. you can report missing achievements and you will be awarded. Just get a screen shot of all five of you units (like when you go to the shop) and report the achievement missing.
LOVE LOVE!! Super hard at first, though, until you get the hang of it. "A ninja must see underneath the underneath." Another true thing Naruto has taught me. Lol.