Hmmm...I just downloaded the upgrade and it is quite impressive compared to the older versions. They ahve actually gotten into this millenium by adding the Tabs and some customization features that Opera and Firefox use. Not sure if I like it yet, but it is a pretty nice feel so far.
I have used Firefox and Opera almost exclusively for 4 or 5 years now, but have always had IE on my PC simply because it is needed for some things that may not work in the others. I also have to check a few different e-mail accounts from the same server often so I keep a few browsers open so I don't have to log in and out of them all the time.
Not sure how I feel about IE 7 yet, but I am pretty impressed so far comparitive to the old ways.