I know I'm risking the wrath by many by saying this! Let me start by saying I do not use my iMac for work. I don't have advanced apps on it like Photoshop or other video or photo editing software. I can appreciate how those advanced users have had issued with upgrading because of probable issues with incompatibility issues. And I know others have had issues with Wifi, something I had an issue with in SL and had to reinstall it, doing a clean install, to get it right again. I played it safe. Made a new partition on my HDD and kept SL in case Lion didn't work out. Did a clean install of Lion via the boot disk and it installed without any issues. Manually dragged music, photos etc over then from the Time Machine external drive. Downloaded then the usual programs like handbrake, RealPlayer etc Been running it for just a day as well so I'll need to wait a week or more and make sure I use it totally and use sleep, wake etc continuously. I have to say my impressions so far are very positive. I love the no scroll bars on display, especially in Safari. It just looks slicker and more modern. And Safari seems to be blazing fast. I love the movement scroll from page to page. I'm no slavish, Mac fanboi. Bought in 2006, the Intel iMac 20in and it lasted me until this summer when the HDD died and got the new iMac. I have used iPhone from the off and also love my iPad. So I can see why Apple are taking features from iOS and brought them into the Mac. It's no big deal to me, but I can see what many might not like them. The reverse scrolling takes getting used to and the Launchpad is an obvious tip of the hat to iOS and doesn't really seem necessary for a Mac seeing as you have the Dock there and Spotlight is already an excellent way of launching. Plus your apps folder is already on the dock anyway. I loved exposé and Spaces and I actually like Mission Control. The desktop spaces at the top is fine imho and easy to work. The new expose you could say is a bit meh, things can get cluttered there compared to the old way. but overall, I like it. Only quibble about Finder is the lack of color icons in the side bar, I miss that and I think many others do as well. I love the new mail, a great app for sure. What I really like about Lion is gestures. I have the trackpad and love the control gestures now gives. Moving from desktop to desktop, scrolling from page to page in Safari, I love it. Resume, I could take it of leave it. It could be a lot more useful If I used my mac for work purposes and were creating and editing a lot of documents. But then again, many users have made it clear that they don't like this and would like "save as" back. All in all, so far, I'm impressed. It feels slick, it seems stable (for me) and I like the new features built on from SL which was a great version of OSX.