Julia Roberts is a mistake. Sorry, but I've never enjoyed any of her work. Yeah, she looked pretty good in Pretty Woman, but I hated that movie too. Something about her really irritates me. Is she short?
As far as DiCaprio goes I'd suggest it's just image stuff he's trying to keep up. He is a decent actor (I'm proud to say that I've never seen Titanic and nor has my wife) but people get smug at times. Spiderman I & II has been a great series. He should be so lucky to be in those movies. Star Wars? It's meant to be campy fun, something that Jackson clearly gets, I just wish Lucas would re-grasp the concept.
My opinion on Christensen has done an excellent job of Anakin. He plays the petulance and brooding part very well, IMO. The chip on his shoulder is almost palpable and he just looks downright sour. The pre-production shots of him with long hair are nicely similar to Mark Hamill so the family resemblance factor is in place. Those Skywalkers are all just whiny little *****, ain't they?
McGregor has been fine for Obi as well, at least to me. He's done a nice job of being that really anal sort of character that Obi needs to be. If I have a complaint about him, it's that his character (not McGregor's) fault hasn't really shown much compassion like Sir Alec's version did. Might just be the passing of time thing, or something lacking in the script, but the original Obi seemed like a nice, old man. Ewan's Obi seems to be overly tightly wrapped. This is not to say he has not pulled it off magnificently.
I completely agree with Scott on Portman. A beautiful young woman, no doubt. But she was wooden in the first and only slightly less wooden in the second. I confess to not having seen her in other roles, but is it poor scripting or poor acting? She seems personable enough in interviews. I realize the role requires a certain amount of decorum, but really, even when the scenes were 'relaxed' in nature, she still seemed stilted. Only a couple of times could I actually bear seeing her on screen. Everything past the time they leave Tatooine was fine, prior to that was painful. And btw, she runs horribly. That scene after she falls out of the ship while chasing Dooku, then gets up and runs? Bwahahahaha. Please tell me that was cgi. Not an overly coordinated/athletic woman it would seem. Just an observation, not meant as a criticism.
Changing topics entirely, don't waste money on The Flight of the Phoenix. Interesting enough that I didn't look at my watch, but waiting for the video will not cause any undue pain and it'll probably be out in about six weeks. Interested to see the original though.