Ender's Game was my favorite book when I was in Jr. High School. I've read it a handful of times--the last about a year ago. It does, however, have the knack of being "just not as good" upon later readings.
I think the problem is, most people first read it when they're young and it's a really fun story and quick read. However, once they become more educated and experienced its flaws really start to show. It is very poorly written and suffers from a lot of the same problems as much of the Star Wars EU.
Speaker is definitely better written. It takes the more classical science-fiction approach and succeeds on most accounts. Ender is grown up and so is the story. I also think it stands up better upon subsequent readings and does hold up well on its own. Maybe you just try that first?
The rest of the series is just awful. As Hyperspace pointed out, the big twist at the end of Xenocide is just completely out of left field. But its real problem is Ender gets demoted to the B-plot and the main plot is just friggen boring and utterly uninteresting.
Children is just a good old fashioned wast of time. I think both stories would have been better served if Card had omitted a lot of stuff and merged and truncated them into one book, wich, as I understand, was what he was originally going to do. I guess he was just after the extra paycheck.
Another lingering problem they each have (And it's one that gets much worse in the Bean series.), is Card's overbearing heavy-handed theme: "Be a good Mormon; make lots of babies."
The nice thing about Ender & Speaker is he keeps the politics out--well, for the most part.
