I'm not sure how many people played Targ at the recent (70-player) Spanish tournament, but from what I've seen of recent tournaments, Targ hasn't been a very popular house. I think most of it comes down to draw...Targ often comes out fast but can't keep up with other houses (especially the control houses) in the medium/long-game.
I've written up my thoughts in an article here http://bit.ly/gTcvBU . The article is directed more at newer players (a la "How to build a Targ draw engine"), but also goes into why (I think) Targ struggles so much, despite the fact it has the most powerful locations/attachments, and some of the most powerful effects in the game.
If people have alternate theories after reading, I'd love to hear it!
(or we're all really just a bunch of idiots that don't know how to play the "you need uber skillzzzzzzz to play me" House...yeah must be that...definitely not the card pool...)