I went with my kid yesterday to see it (in 2D...because F 3D, that's why). I've never read the books or anything.
I thought it was pretty decent, and was pleasantly surprised. A wouldn't say it had anything we hadn't seen before (and the tournament scene was a retread of countless other scenes, but combined with the desert setting, it really was reminiscent of Attack of the Clones). It all came together pretty well though, and other than a couple lines of dialog, some bad wire work, and a couple things not being fleshed out a bit more, I have no complaints. Like I still don't quite understand exactly what the Therns were doing. Something about overseeing the death of a planet or something, I guess.
And Lynn Collins is nice to look at.
Regardless, a decent B-movie sci-fi. Doubt it will ever become a cult classic though, as there's just not that much different about it that would warrant it. I'm not really sure where the 250 million went (assuming that budget is accurate). Yeah, it had a lot of CGI in it (and decent CGI at that), but no more than the Star Wars prequels or Lord of the Rings....both with significantly less budgets (Avatar even came in a bit under 250M). Maybe the 3D conversion the previous poster who mentions that could cost up to 10k per frame bumped it up that high.
Regardless, I have no dog in the "will it make money or not" or the "how big of a flop is it" fight, so don't really care. Continue to argue amongst yourselves