I just received my Gateway today and it works like a charm for what I have tried. Some people have had varying luck but it's no different than any other piece of hardware. There are also rumors that the clones are "copying" the software from Gateway which doesn't mean they won't work, but it could mean you may have to wait longer to get updated features. There is also a rumor that the clones hardware are not able to support everything that the Gateway is promising (multi-rom, etc). But like I said these are rumors. I know the cheaper price of clones are enticing, but I have learned that in the case of flashcards higher price usually means better features and support (just my personal opinion though).
About the DS card that comes with it... the reason it doesn't work on later firmware is because it uses an older version of the custom WoodR4 firmware that isn't compatible with 6.2+. This doesn't mean that someone can't find a way to add support for it later. I am lucky enough to already have a Supercard DSTWO to play DS roms with though.