Tried it and Liked it!
I was part of the BETA, so I got a chance to play quite extensively. If you like the real thing, you'll probably enjoy the virtual version. Game play is easy to learn and use and there always somebody to play with. Plus, no arguments about the rules.
As for costs, I think there are a couple of deals floating around for opening accounts. I know the game itself is free to download. In terms of laying out allot of cash to build a deck, this is probably true if you want to build tournament type decks. But, what I did is join a League which last about a month, it cost me a deck and two boosters plus two tix around $17 US. I get two play against other people in the League with the same quality of decks, so I know I should be competitive. I only have to buy 1 booster a week and at end I get to keep the cards that I got. Plus, if I finish high enough I can win prizes (more cards). Not too expensive for a month of playing.
Also, you can join booster drafts which cost 3 boosters and 2 tix for around $11 US. Again, you keep the cards and you can also win more cards.
Cheers,
Al