Well you could search here to view all the opinions....
More generally, what are you going to do? Upgrades aren't just about features, they're also about fixing existing bugs, improving security, enabling new hardware, etc etc. Sometimes you can skip a maintenance type release, but eventually you're gonna have to upgrade, unless you just want to freeze the existing software and hardware you have. It's a fact of life in computing.
And I can summarize the general opinion: most upgrade. There are more Mac users running Lion and Mountain Lion than running Panther. Eventually most everyone does, and most of what you see here, by contrast, is the people with the problems. Not many of us are likely to bother to go online and say "I installed Mountain Lion and meh, it works." About as newsworthy as uncapping a new tube of toothpaste, but nevertheless necessary eventually.