Nintendo DS Hardware/Emulation M3adapter

Alright.

I've been really wanting to get this.
http://www.m3adapter.com/products.htm

So that I can play Nes roms and backup my DS games.  But I'm not sure if I want to pay for it without first talking to someone who has had some experience with it.   So, Does this thing work well with playing backups and downloaded roms?   How well does it preform with NES roms.   Is it a waste of $?

Outside of this and flashcard, what else would I need?

I've got one. It works well for playing commercial roms. Depending on your firmware you'll also need a passme v1/v2. I haven't had any luck getting nes games to work but I can't say I tried very hard. Also the added bonus of running cool homebrew apps is very much worth the dollars.