I got the K books for DD and she loved them. So I decided to try them and bought the whole 2nd grade for my son this year. (we had been using a mismash of things that I switched a ton of times and hadn't settled on) I *love* some things.
Reading: I love that it's Bible based. He's getting a solid foundation in the Bible. It seems to be the right level of challenging. It's gotten easier as the year's gone on, and his reading has really taken off. The work mostly has a purpose, not repetetive busywork. Some of it is, and I let him skip sometimes, but most of it's useful to some degree.
English: I've heard it's very thurough. It's very gentle, which seems liek it'd be good for slow and fast learners. It's easy to tweek to speed up. Or with a slower child, it'd be a good pace. Either way, they *know* grammer when they're done.
Math: Ugh. Don't ask me, I find it incredibly boring. I don't care for the cute, unnecessary posters. DS likes putting bees on the poster, though, so what do I know :) It seems to move incredibly slow, though. But I've heard good things about it being thurough. I think it'll work well with DD, but with him I feel like it's holding him back and not pushing him to his full potential. On the positive side, he is learning his math facts.
SS- I don't do this. We do have the books, and he does them on his own when he wants to. Same with Science. He really likes the science book. It's about nature. It does tend to be regional.
All in all, we'll be keeping the reading and english. And the books are so cheap we get ss and science for fun extras. Math, who knows. HTH