Agree with MacAddict1978 100%.
[Since I've started my Mac experience with Leopard (and Snow Leopard on my private Mac) I guess I don't have enough "street cred"
, but I'll throw in my few cents anyways.]
Both my 13 and 15" MBPs came with Lion and I've upgraded to ML - gotta say I don't see much of a difference, I didn't have any issues with neither. But my girlfriend running SL on her 2007 white MB also doesn't have any problems with it. It runs just as smoothly and fast as it did a year ago when I bought her the MB and installed SL on it. Plus she can tweek the icons with Candy Bar which she likes very much - it's a small thing, but important for her
As for Lion/ML - sure iCloud integration is great, especially after a while when you get used to not saving things on your HDD and then copying them to pendrives other Mbs when needed etc, but still that's something one can easily live without. And it comes with a downside, like when your web connection goes out or you find yourself in a "web-less" place
Then what? You still need "hard" copies.
As for ML I can't realy complain since like I've said I don't have any issues, but the "new" features are truly a laugh:
notification center - ok, cool, probably someone's using it, but not me. Wanted to turn it off right away, but it turns out you can't - gotta use a termninal command. WTF?
battery indicator - seriously? Why did they change it? For the sake of it? As if "80%" tells me more about how much longer I can run on battery than time indicator. Gotta install another app just to get it back. Come on! Hope they'll bring it back in 10.9 and they'll probably hype it as a new cool feature
Facebook, twitter etc integration - cool, it's more of a tweek not a feature and honestly I could live without it and spend a minute posting a pic to facebook.
Game center - haven't used it once and I'll probably won't. I'm a "Sunday gamer" so to speak
Launchpad - ok, I've even found myself using it more often that my Apps folder in the dock since I can arrange program icons according to my preferences. But still, they could just make the Apps folder (put in the dock) act like launchpad, no need to double "beings".
notes - great. No complaints.
reminders - OK I guess, but I don't use it. I tend to remember things
But if someone has lots of appointments etc it could probably be useful.
Can't think of any other issues or regrets about ML. All my software that worked on SL - most importantly Adobe and Office work great, but obviously the whole Lion/Mountain Lion upgrade didn't really feel needed from my point of view.