I would not buy them unless I was going to use them soon. I have had 4 in the past few months become invalid because the place is no longer accepting them. They do let you swap it for another but its a pain in the neck when you go to the place and they tell you they are not participating anymore!
I also would never give them out as gifts since they are more of a coupon than a gift certificate. If I have to spend 25.00 to use a "gift" of 25.00 then its really not a gift...