I don't really think anyone can say this film sucks, that’s not to say it's a brilliant film, but it certainly had its moments.
Jango Fett versus Obi Wan was a very exciting fight and Yoda versus Dooku was more than I could have hoped for and worth the admission fee on its own, but these highlights were let down by some bad acting by Portman and Christensen, poor dialogue and a Tom and Jerry-esque scene on a conveyer belt.
Christensens acting was inconsistent. I was impressed in places, especially in the scene after he had returned from killing the sand people, but a lot of the time he just came off as a spoilt brat rather than a frustrated Jedi. I didn't really believe the forbidden love between him and Portman either but I think this also has to do with the script, which was bad in places, and without the talents of Ford and Fisher didn't quite work.
The story line was again very political but it went some way to bridging the gap between episode I and episode IV. There are still many important events that must take place before ANH which will (hopefully) make episode III very dark indeed. Unfortunately, the continually cutting between different characters in different locations sometimes broke the flow of the film and meant you didn't get particularly interested in the situations.
I enjoyed seeing early versions of the AT-ATs and the combination of star destroys and the imperial march themed music at the end made the hairs on my neck stand up but I think this was more due to the association with the original trilogy than anything else. Also it seemed very perverse when Yoda was controlling the clone army!
Despite my criticisms I enjoyed the film and I think when viewed as part of the whole star wars saga it is a success.