I discovered Acid Test a while back.
Decided to run IE8 against FF2. Results:

(In the shot is just Acidtest 3 and 2; they both passed 1 easily of course)
Then when I was about to upload that image, I get a popup saying:
There is a nice feature I noticed on IE8, "Webslices", which is essentially a combination of Bookmarks and RSS Feeds.

The icon will then become bolded if there is an update for that page.
You can then click that little arrow to see really quick what the updates are (Like a mini RSS feed window) without having to load up the page

They advertise how it can work together with Facebook to see all your friends' updates. I can't honestly say I care THAT much about my friend updates on Facebook.
I can't really see myself using this Webslice feature. It's a neat little toy but eh. I like to let all my feeds add up for a few days and then just spend a while reading them all. I'm not the kinda guy who needs minute-by-minute updates on celebz and my friends. On a little advertisement video, they showed the usage for eBay(it'll update you if an item gets new bids), and I guess that might the the only function I'd ever use... if I was an eBay person.
The main reason I'll never use IE8(nor IE7) is just how goofy it looks. The artwork to show the tabs is too bubbly and oversized for me, and there's no decent way to downsize the whole top section.

(That button I can't get rid of? "Emulate IE7".)
So there you have it, Xoxide. My strongly opinionated took-2-minutes-to-hate-ie8 review of absolutely every feature IE8 has to offer you. I guarantee it! *Goes back to hugging Firefox*