I've used IGN 5 about 5-6 times overall.
They have always come through on their delivery, although once or twice I had to wait a bit due to high demand at the time.
The reason for a 4 star review is due to the fact that once they get your e-mail adress they will spam you with discount codes mercilessly. I probably get 4 e-mails a week from them on a good week. They are always from different random addresses too, so you can't block them. These are just the ones the spam filter doesn't already catch.
So, I wouldn't say they are bad, but, use a 'temporary' or 'junk' e-mail address when ordering.
It's not all bad though, just the spam thing annoyed me. The prices are very good most of the time with a discount code.