Having not seen the original 'Clash' in 1981, I am judging this film as any other film - not comparing to it's original, just a average movie review.
'Clash of the Titans' (as said) is a remake of the 1981 film of the same name. The story follows the Greek myth of Perseus (Sam Worthington who you may know as Jake Sulley in 'Avatar') who must capture Hades, the god of the underworld (played by Harry Potter's nemesis, Voldemort, Ralph Fiennes) while Zeus (Liam Neeson) tries to guard Hades' wanted revenge after Zeus tricked Hades and sent him to the underworld. Perseus has a very difficult task: He must defeat Hades, the infamous Medusa (the one you don't want to look in the eye, remember?), and Hades' created creature, the kraken.
First off: Casting. Sam Worthington seems to get mixed reviews on his acting by some critics - some love him, some are medium on him, some can't stand him. From the two films I've seen him in now (Avatar is the other) I have found him to be a pretty solid actor - not amazing, but he has delivered two very nice performances in both films I have seen him in - he was the main character\good guy in both, too so you get to see plenty of him. So with that being said, I thought Worthington played Perseus outstanding - some of you may have other thoughts about his performance in 'Titans', but I thought he played Perseus great.
Ralph Fiennes is also rock-solid as Hades - you really feel his "evilness" in the film - other villains in other films aren't acted as great, but I think Fiennes was perfect for the role. Lo (Gemma Arterton) who had kept an eye on Perseus throughout his life is a very beautiful character and likeable, too. Arterton was also rock-solid in her role. Liam Neeson on the other hand... some reason I had mixed feelings on his role as Zeus - he was good, but not great. I don't know what it is (I will probably get questions on why I didn't like him as well - I honestly can't say - just something about him seemed a little "off" but to each his own, right?) Mads Mikkelson (sorry, I can't help but laugh at that hilarious name) plays Draco great, too. While Princess Andromeda (surprisingly doesn't have that many scenes when you consider she is a princess after all - but I haven't seen the original yet, either, so.. yeah.) who is played by Alexa Davalos is pretty good, too. I didn't see many flaws in the casting in this film, either besides maybe Neeson as Zeus, but even he wasn't terrible.. so I think the cast is all around nothing short but great.
One of the big highlights in this film is the amount of badass creatures and villains - some fierce creatures and villains were aplenty in this film (especially creatures) as it seemed there wouldn't be 5 minutes without some kind of battle going on. Which is a very good plus since that brings much action, and much interest in viewers. So I give action a A+. I also got to mention that the movie goes by very swiftly - it goes by rather quick. (It's 106 minutes, by the way).
One thing you guys may want to check out (if you don't have a Blu-Ray) is a interesting alternate ending that came to the Blu-Ray version of the movie - so you might wanna search "Clash of the Titans Alternate Ending" on Youtube to check it out if you don't have Blu-Ray (like me).
I have to say that I was pleasantly surprised at how good this film was - casting was very good, villains and creatures aplenty, and action non-stop. I may shock some people by saying this, but I have to give this film a 9.5\10. Because I just feel that if I made it a .5 lower, it wouldn't be right. I recommend checking this film out for sure - it will be worth the rent!