Hey conclusion was that it's "fucking gorgeous." My opinion was somewhat more moderate. I definitely liked it more than 300 (but note that i was none too fond of that) but didn't like it as much as Watchmen. The action scenes were definitely cool. Despite what the reviews said it actually had a decent and compelling story in between the action bits. However it should be noted that the story was rather depressing. It wasn't as bad as my initial predictions when i first read the premise, but it's also far away from "and everyone lived happily ever after."
It's also important to note that it's not a case of "there are parts that are fantasy and parts that are not." The very beginning and very end are 100% real. The fantasy/sci-fi action bits are 100% fantasy, well at least 100% metaphor anyways. Everything else is on a sliding scale of fantasy/metaphor that can be hard to pin down. We spent awhile after the film debating what exactly happened in reality.
The action scenes were very pretty and unrealistic, but they all take place in a fantasy world so that's okay. The first such scene pretty much manages to compress the story arc, or perhaps more accurately the "fighting" arc, from an entire season or movie of shonen martial arts manga/anime into about five minutes. A later scene mashes-up World War I, steampunk, and mecha anime. They're all relatively short, but on the plus side that means they never reached the point of feeling like they were being needlessly dragged out. Always leave the audience wanting more and all.
So if you're okay with a two hour movie, with around 40 minutes of action-packed fantasy and a little over an hour of depressing reality mashed up with metaphor that put it up to question exactly what's going on, then you'll probably like it. If the fantasy action part doesn't appeal to you, or the 60-80 minutes of "reality" that you can't be quite sure of seems like too much to go through, you'd probably be bored to tears.