jedibuttercup

Yes, by the time of Diplomatic Immunity I think Bujold was running dry on Miles ideas - probably she'd shifted attention to her current series "The Sharing Knife."

I've read every Vorkosigan book she wrote, several of them twice. The Vor Game (next in the series?) is very good. Mirror Dance is good. Cetaganda is good, Komar is good, and the short stories (especially "The Mountains of Mourning") are excellent. However, I had trouble with Memory and those proceeded it: they got very dark and hard to read. At least for my tender sensibilities. :}

As for the rest of Bujold's work, I personally did enjoy the Challion series, and am currently enjoying the Sharing Knife series. But I'll admit they're not Quite as good. Frankly none of her characters measure up to Miles, although most of her main characters share many of his characteristics.
She also has a couple of off-series books in the Vorkosigan universe (Falling Free and Ethan of Athos) and they're good reads too.