Very occassional problems with lock ups on some web sites, still use ie for some sites that refuse to go standards compliant and obviously check my designs in ie.
I've also been following with interest the Opera vs. Firefox debates which are cropping up more frequently.
I use Opera every now and then, but without extension support, it's not as rewarding.
Interestingly enough, this seems to be most peoples feeling - extensions are the "killer app" for firefox, without them, I'd probably switch to Opera because it renders pages quicker and caches them better.
Apparently, Opera has better support for web standards than Firefox, but there isn't much in it.
Firefox has now reached the point where any serious web dev designs for it, to ensure compliance to web standards and then hacks alternatives into the code for ie.
Also waiting to see if the allpeers.com extension will make as big an impact as it's developers are indicating.