As far as I know, he just put a new hanger on there.

I spent an hour or two working on it in the garage this evening, and couldn't get it shifting much better than it was. On the stand, it would not upshift cleanly through the two largest sprockets, no matter what I tried. Going from 3->2, it overruns and seems to settle the chain on the outer edge of the largest sprocket, with noisy and slippy results.

I was following the Park Tools guide and it all seemed to make sense, but still it won't shift cleanly. I suspect under a little load it would perform a great deal worse. Nothing is visibly bent or out of alignment, as far as I can tell.

I plan to take it to another store tomorrow morning. It's a bit of a drive, but it seems to be time for a second opinion.