As a new member and a new MtG player (the things I missed in high school and college -- [sigh]), I find myself having to be mindful of where I'm putting my cards in from the inventory and into decks. I don't have very many, so if I build multiple decks that share some common artifacts or colorless cards, I find myself checking between decks to make sure one of these cards isn't in another.
That's really the only beef I have with this site so far. It's terrific, and VERY HELPFUL to new MtG players trying to make sense of their inventory.
Regards,
nthdegreeburns