I have just installed the update on my Wildfire and am now running Android 2.2 with HTC Sense.
So far, so good.

My main issue is that it seems impossible to kill tasks now. I was using Advanced Task Killer, now I am using AVG. Can anyone suggest a way of sorting this out, or failing that, recommend a decent 2.2-compatible app killer?

You dont need a task killer in 2.2. The operating system does this for you - check out the settings.

Thanks!

It does seem a bit slow to do, and certain services like the Yahoo push mail service seem reluctant to stay closed. Still, it's better than nothing I suppose.
All it needs now is a one-touch close-all script of some description... *searches*