It's been hit or miss the last few months but overall it has been totally worth the $15 subscription. I joined last June, the month following the coupon group than included Batman: Arkham City for $10. I used at least half of the coupons for the next two or three months but then it dropped off as far as fantastic deals. I think I didn't use a single one from the December issue. So far for the current group, I snagged Prototype 2 for $5.
Still, even if you don't use any of the coupons but do take advantage of BBY's trade-in promotions, the sub can pay for itself. 10% extra TIV plus double RZ points adds up quickly. I don't purchase many used games from BBY either but every once in a while there could be a decent game, so another 10% off those.