Actually, much like December movie studios are now starting to release major films outwith the summer season because it's been proven that you can release a blockbuster and make good money out of it.
This is especially true with the December holiday period (last year Sherlock Holmes, Alvin and the Chipmunks 2 and definitely Avatar took great advantage and ended up with huge takings. Which is no doubt why this year we have Tron: Legacy, True Grit and more scheduled for December 2010, and already Mission: Impossible IV and Spielberg's Tintin movie scheduled for December 2011) but also April is starting to prove it can deliver good grosses (300, Fast and Furious 4 and Clash of the Titans itself have demonstrated) so I think while the traditional for the last few years summer season won't go away, you will see more films at different periods.
Which I think makes sense - as the summer season itself becomes ever more crowded with wannabe blockbusters it gives them a chance to earn more if you spread them out over the whole year a bit.
And making money is the point of these giant films!
As to Clash of the Titans itself I personally thought it was a very poor film and I didn't enjoy it. Luckily I didn't pay to see it in 3D but I was bored by the halfway mark and the movie never recovered for me. Some of the CGI (the Medusa) was awful. But it's been a big enough hit globally to have had a sequel greenlight last week.
Though Louis Leterrier will not return to direct it.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist