I found these not to long ago as well and just have to say I really enjoyed them. I thought the tone of the later Ender books was different and there was a more overt philosophical bent. That didn't really detract from my enjoyment but the sequels for Ender are of a very different quality to me. Very good but almost a different category.
I've got to say that it is probably not to many writers that would go back and tell the same story twice using a different character as the main person. But Ender's shadow was so good it made me wonder if is surpassed the original. (I decided I like the first one better) The follow up books on Bean have been really enjoyable. I kind of feel like they were less philosophical then the Ender sequels and more of the action adventure style. And yet Card surprises me throughout all his Bean and Ender books with some thoughts that really made me stop and think.