Over on the Ars Technica discussion boards, a user known as falku has posted a pretty detailed rant about his many problems with Apple's Mac OS X 10.7 aka "Lion." He concludes:
Lion is LAME. It feels hardly snappier than Leopard on my 667 Mhz PowerBook from 2002 and not at all snappier than my 2008 MacBook Pro with Core Duo. How much faster is the i7 supposed to be than the Core 2 Duo - 5 times ? I do not profit from this hardware acceleration at all. Yes, the MBP 2011 I tried in the Mac Store indeed was much snappier, but not my own machine. I checked with Lingon for unusual demons but there was nothing unusual. Keynote takes 18 seconds to open a 20MB presentation for the first time. C'mon !!!! (But only 3 seconds some minutes later ?!).
Overall, I am pretty disappointed for the first time in my Apple life. You get the feeling that in the attempt to merge iOS and OSX, the OSX part has been neglected, and I can only desperately hope for future updates. Lion is perhaps not a drama similar to Vista yet not Apple-like.
-"Is Lion Apple's Vista ?" Ars Technica OpenForum, November 25, 2011
Of course, falku is not alone. He (or she) is in good company.