The second Matrix movie is worth seeing for the action scenes. They probably don't hold up very well though, I haven't seen it in a good while.
The third one is just boring all around, and took everything that could have been potentially interesting about the plot of the second one and tosses it all in the garbage.
Still worth seeing both of them imo. Even though they're not very good, its interesting enough to see where it goes. I'm not one that believes bad sequels can decrease your enjoyment of the originals. The first Matrix is still one of my favorite action movies even though I almost hated the third.