This seems like a pretty good deal, actually. Pretty comparable to the B2G1F deals we prize so much, as long as we're shopping for cheap games.
Here's the mathematical comparison, assuming you're buying games priced at $17.99, which is pretty popular. I'm also figuring in an Edge Discount, though I'll give the figures without as well. I'm not considering sales tax, though, since that vaires from state to state.
B2G1F:
$17.99 + $17.99 + $0 = $35.98
$35.98 - 10% = $32.38
Total price per game: $10.80 ($11.99 w/o Edge card)
$5 off coupon:
$17.99 - $5.00 = $12.99
$12.99 - 10% = $11.69
Total price per game: $11.69 ($12.99 w/o Edge card)
So given that you don't have to find 2 other games to get the discount (wehich has sometimes been a problem), I say if you find a cheap game you'd like, then go for it.