You’d be hard pressed to find a more thorough review and analysis of OS X than John Siracusa’s work. He brings the business consistently and his latest review of OS X 10.7 is no different.
It’s long, really long, and well worth checking out over here.
Siracusa’s ultimate recommendation:
Even at Ars Technica, a certain percentage of readers just want to know the bottom line about a new operating system. Is this a good release? Is it worth the price and the hassle of installing it? Excluding the first few dog-slow, feature-poor releases of Mac OS X, the answer to all those questions has always been a resounding “yes.” Lion continues this tradition, more than earning its $29 price with a raft of new technologies and a substantially revised interface and suite of bundled applications.
The standard caveats apply about software and hardware compatibility. Don’t just run out and upgrade your system as soon as you finish this review. Lion’s digital distribution makes hasty upgrades even more likely. Patience! Take a few days—weeks, even—to research all of your favorite applications and make sure they all run fine on Lion. If you’re still using some PowerPC applications, don’t upgrade until you have replaced them with Intel-native alternatives. And before you upgrade, backup, backup, backup.