On the performance side of things we don't see anything new out of the driver. It's funny, but when talking to people it seems that most are sitting on the 10.4 drivers still, which seem to have been the best this year. To be honest, if there's nothing that stands out for you in the release notes, there's no real reason to upgrade.
With the performance bit aside, it's worth mentioning that this driver did cause some issues. When it came to running benchmarks on our machine we quite often found coming out of a game we would just come to a black screen.
Initially I thought it was freezing so I restarted when it happened. At one point I tried the old ctrl + alt + del option and the screen came back with my options menu; I selected task manager and my desktop showed up. I could close task manager and everything went to normal.
Unless you really need to upgrade, I'm not sure I would really bother. The problems we're experiencing mean we'll probably skip these drivers in our ATI reviews. Lately I find myself mainly using the 10.5s.
Little glitches like the above mentioned one can be due to any number of things. It could just be the driver not liking something on the testbed as people haven't reported the issue I'm having. At the end of it, though, like I said, unless you really needed to upgrade, I wouldn't really bother.
Until next month, may all your frame rates be high and your games good fun!