Developer, Former MVP, now at Microsoft - Best of 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
I've been using Internet Explorer 8 since the early pre-release bits, but I never tried IE9 until today – the day the Beta is available. I downloaded it from here: http://www.beautyoftheweb.com/
The download took longer than what I expected, but I was doing other stuff, so no bother. After coming down, it asked me to reboot my computer. Really hate when apps do that, but I did it anyway.
The first time I launched it, it prompted me with a list of add-ons I should disable including the start-up time that I could save fore each one. It even let me configure the prompt so, for example, it won't prompt me again unless an add-on contributes to more than 1 second of the startup time. Cool.
First thing I noticed is that the search bar had gone and, as you'd expect, you have to search from the address box. I totally despise this feature. The first thing I've been doing with all versions of IE is to turn off the automatic searching from the address bar and now I have no way of searching if I do that. Ridiculous.
The second thing I notice is that the tabs are next to the address bar and cannot be moved to go below it. One word for that decision: appalling (and, no, I didn't accidentally drop an 'e' and added an 'l' in the previous word).
The third thing I notice to the right is the favorites button (star icon) and when I click on it, it brings up the favorites explorer under it on the right; then I pin the explorer and it jumps to the left(!). Why move the entry point to this feature to the right instead of leaving it on the left is beyond me (other than wanting to retrain me on what I've been used to for all this time), but the fact that pinning it makes it jump sides is… an "astonishing" design decision.
As I browse I notice a little annoying pop up in the bottom left every time I hover over a link; there is no status bar. I correctly guessed to right click at the top and turn on the status bar (which also got rid of the popup thereafter) and while I am at it, I bring back my favorites bar which was hidden by default (and am pleased to see that all my favorites are still there).
The next thing I notice, I like: IE9 is fast. No joke, I visit sites and they seem to be loading visibly much faster – try it!
Beyond the speed, I am interested to find out what else is new. I searched and found a few good links:
If you are a developer, check out IE's msdn home for many articles, e.g. this section on Canvas and SVG.
Either way: wherever you are, get IE9 Beta now and judge for yourself. If you don't like it, you can always uninstall (which auto-restores the previous version).