It's a great film, very difficult to watch near the end but really good. The material is very adult even though there's almost nothing explicit: no profanity, almost no onscreen violence (except against monsters and robots), and no sex or nudity beyond a lot of thighs, a bit of cleavage, and the odd bump or grind. But the scene where Blue shoots Rocket and Blondie - God, that's brutal, it just builds and builds with no mercy, and then there's the sound of the gunshots and you just want to crawl under your seat.
After the first viewing, I think I was still a little hazy on the exact sequence of events, and was clinging to some idea that Baby Doll was spared the lobotomy at the very end. On the second viewing, I took in the blood on the surgeon's instrument (even though Baby Doll is shown later with no apparent scars).
The film has the grimmest of happy endings: Sweet Pea does escape in the movie's "real world", like her fantasy analogue, and the rest of the inmates of Lennox House are apparently rescued while Blue is arrested and (we hope) brought to justice.
So the story ends tolerably well for Sweet Pea. (I love that name - it connotes both innocence and poison, like the wild plant that proved the undoing of poor Chris McCandless in 'Into the Wild'.)
One reviewer described Sucker Punch as "what you'd get if you mixed Mulholland Drive, Showgirls and Tomb Raider" but for me the obvious comparison was with Terry Gilliam's 'Brazil' (and Zack Snyder said as much). It's not just the surreal, pan-twentieth-century ambience that Sucker Punch shares with that movie (and with 'Grind House'), or the obvious nod to the final scene; it's the combination of a dystopian (but all-too-real) world with the mind's power to escape. What Sucker Punch adds to that, though, is the power of the imagination and the subconscious to provide us with the clues and the courage to fight and change the reality.