Assuming your goal is to play good bridge, you need to do both: reading and playing.
Reading will make you familiar with the distilled thoughts of experts, card play techniques, bidding issues etc, which they arrived at, after having had years of experience. It is unlikely that one single individual will ever gain that through his/her own playing experience.
While in theory this is all fine, to play good, winning bridge, you need to be focused at the table, and be able to do: Counting.
Being able to count the hand (high cards, distribution) is the single most important ability which separates the good players from the average player, and for most this only comes from playing. Not counting vs counting is compared to driving blind vs looking where you are going.
If you want to learn things quickly: do some reading, play some hands and do a post-mortem of the hands you played with a better player who knows the stuff. Rinse, Repeat.
The best way to learn and improve is to actively look for your mistakes (which can only happen if you actually play), ideally by doing a post-mortem along with a player who is good enough to figure them out.
I would highly recommend you read this blog post from Justin Lall (who won the silver medal in the recent world championship: Bermuda Bowl): http://justinlall.wordpress.com/2006/04/26/how-to-improve-your-game/