Internet reviews play a big role on my buying decision since I'm less likely to buy something which was rated 2/5 stars average from 200 buyers.
If a game is rated 4/10 by most game sites like IGN, Gamespot, Gamespy, etc and its users then I porobably won't get it unless I am a huge fan or played it at EBworld and I enjoyed it.
I agree that word of mouth is pretty good at convincing me that something is worth buying, but unfortunately some things don't have refunds like food, mesages, services, movie tickets, and concerts.
For video games, NO. I usually don't agree with the reviews that games have been given anyway.
But for other products (like the Kindle I'm still trying to decide if I want to get), yes, I'll look at reviews and read other peoples comments about the item. It may not completely sway me one way or another, but I like to be informed.