I've watched all three now and I can honestly say that the first two are among the most entertaining movies I've seen recently. Beautiful cinematography, wonderful settings, a great, well chosen cast, and fantastic fight choreography. There is some wire work involved, but there is also a lot of physical work on the part of the actors, especially by Takeru Satoh who plays Kenshin. There are several scenes where you're not sure if you just saw some very subtle wire work or some really amazing, Jackie Chan in his prime, style maneuvering. The stories in both films are entertaining, the plot moving along nicely, while not feeling rushed.
Unfortunately the third film falls down in the story department. The second film starts the Makoto Shishio storyline which is considered the highlight of both the manga and the anime. With the third film the film makers tried to fit the rest of the storyline into one film, which led to a story that was rushed with minimal story used to tie fight scene after fight scene together. You still have the great looking film, acting, and fight choreography that made the first two films so enjoyable. But by the time you get to the final battle, you're burned out. The fights impact is lost because of the extended scenes of battle that preceded it. It's still a film worth watching, but falls short compared to the previous two.
So overall a trilogy worth watching, especially if your a fan of either the manga or anime, just be ready to be worn out by the end of the third film.