I started out using Mac OS since 10.2. I got my 2011 MacBook Pro that came with Lion. This is the fist time I've ever 'downgraded' back to an older OS.
Therefor, not content at all.
Mission Control is an absolute mess and until they fix it with options to bring back the old proper Expose, I'm not switching to Lion, my productivity when multitasking is killed.
I heard about heat and battery issues but was never able to test Lion enough to judge it in that respect, Mission Control was an immediate turn off so I switched back before running any more tests.