I kind of liked it! Yes, the dialogue was cheesy (as to be expected), but I do agree with Matthew, who argues that it was not quite as bad as the dialogue in Episode II.
The special effects were stunning, the fights were entertaining, and I actually found the story compelling — i.e., I found myself feeling some of the emotions that the audience was supposed to feel. This is certainly more than I can say for Episodes I or II. While not a great film, it was quite enjoyable and a fitting end to the series.