Due to some fortunate circumstances, I was able to partake of the Matrix goodness ahead of the release. Overall, I thought the movie was excellent, but there were some issues (for me, at least) that kept it from being spectacular. It's definitely worth seeing, and if you're worried about it not being that good, go see a matinee screening and skip the popcorn. ;-) It is a blatant cliffhanger, though, so if that drives you nuts, you better just wait until November. Keep reading for a more in depth look, and I'll try not to let any spoilers slip.
The special effects were great. I personally didn't see anything totally revolutionary in them... it seems like most of it was simply "bullet time", but more refined, utilizing CG where cameras don't make it. Only a couple of times did I feel that the CG wasn't quite right, and even then it wasn't due to the impossibility of the action. It was mostly due to a character's arms/legs/hair/clothes that didn't move 100% naturally during a stunt, which is definitely difficult to get right. There was only a couple instances in 1 scene that come to mind immediately, so the effects people did an excellent job.
One of the main criticisms of the first Matrix was the lack of character development. Well, I won't lie to you... there's not a whole lot of character development in this one either. There was more, but not for any of the main characters really. A little more insight into Morpheus's life, a new take on the Oracle, the introduction of some new characters, and the whole thing going on with Agent Smith. But there are still a lot of gaps in the characters, but Reloaded does make you feel like you're starting to understand things better, and that the next movie will be very enlightening.
One of the best after-effects of the first Matrix was the way it made you question your own take on reality. It really made you wonder what's real, and what's not. What's important to me, and what's not. Or maybe I was just being overly philosophical about it. Reloaded really does a good job of leaving you questioning, but this time, you're speculating about the movie and where it will head... how things will be resolved. Reloaded ends with many loose ends, and many questions unanswered, but at the same time, it's an excellent opportunity to speculate. I definitely want to see Revolutions now, and it's a good thing I only have to wait 6 months.
The movie also flowed well. I didn't ever feel like a scene was put in "just because", except once. I personally felt that the love scene between Neo and Trinity was a little overboard, and that a lot more could have been said with a much more subtle approach. Intermixed with this, were shots of the people of Zion having a wild dance party/orgy. Ok, so the orgy was implied with the whole sexual nature of the dance scene. I couldn't help but relate it to Herbert's Fremen spice orgy in Dune, except without the spice. It struck me as the same type of situation.
To sum it up, I really enjoyed it. My only big complaint was the love scene, but I am a conservative person. Other people will undoubtedly love the movie just for that scene. The rest of the movies was great, and definitely sets up Revolutions as a must see.