I think it's a limit of one coupon per purchase.
Yep. So if Skyrim comes up on the Best Games list, for example, you'll only be able to use one of the coupons/credits. I managed to snag a $5 credit for a 47 cent purchase of the Blood DLC for Shogun
And for those iffy on Cities XL: it is basically an expansion to 2011 as others have mentioned. I haven't tried the extra stuff in 2012, but do have 2011. I like it as a change of pace from SimCity 4. Cities played basically is more macro to SimCity 4's micro on the city level. Once to the inter-city metagaming, it's about equal depending on tastes. Though you can go uber micro on Cities by placing individual buildings of your choosing. I also found Cities to have much better traffic simulation compared to an unmodded SimCity 4. Graphics are really nice to boot.
That being said, the fact they STILL haven't fixed the engine limitations is just mind numbingly frustrating. Though I think they might have tossed in a fix to break the 32-bit memory limitations, which helped with crashes on larger cities. Performance still goes to crap, though, due to a single core.
Hrm..I think I might pick it up :/ I liked Cities even with the frustrations, kinda like how I still enjoy playing SimCity 4 even though it requires voodoo dances at times to get working. Amazon is still running their deal where you get 10 points/$ on digital downloads on the Amazon card, so hey, I save a buck or two.