Yup, I find them to be more affordable than Gymboree (and I am addicted to both) if you shop them right. You never see Gymboree run a "40% off the the entire store" sale. 30% off is as good as it gets at Gymboree.
They do have bucks earning/bucks redemption, but they don't seem to run those as much as Gymboree does (where you are always either in earning mode or redeeming mode). They just had redemption about 2 months ago, not sure when they would start again. I would guess around BTS or so.
The bonus cards for $15 off $40 are earned during earnings time, too. You get a card for every $50 purchase, but frequently it's ALSO during Justice Bucks earnings, too, so then you get $40 in coupons for $50 in purchases. (One Justice $25 off $50 coupon, and a $15 off $40 coupon).
The $15 off $40 coupons are nice because they have a LONG redemption period, which is nice. About 6 weeks or so. I have four cards that don't expire till June 28, I am hoping they have some BTS type clothes in by then.
Oh, Justice has a MUCH better return policy. Gymboree will rake you over the coals if you try to return something that you earned Gymbucks on. Justice doesn't do that. And none of this "keep your receipt stapled to the buck" crap, either. The buck is a tiny little card, like a credit card, you can keep it in your wallet (and I DO!) you can give it away to whoever, spend it, whatever.
The retail prices are very similar to Gymboree on most things but some things they are cheaper. Justice is $22 for the knit skorts, Gymboree is $26, tees start at $20 at Gymboree and Justice $16.50, etc.