I see Second Life as a "world" for people who can't make it by in their own life, and are left to resorting to a computer to attempt to sell fake clothes for money and make an avatar who is "good-looking" because they're ugly. There is no need for a Second Life, I have a fine first life right here on the earth.
World of Warcraft and other MMORPG I am generally not a big fan of. I expecially disagree with the monthly subscription fees for some games. It reminds me of Napster and Rukus, but you don't actually get much useful stuff out of it. MMORPG's without subscription fee's are better, but I'm not a really big fan of them, mainly because I don't really like RPG's in the first place.
I think this video on YouTube sums up Wow pretty well.