I did only because my tutor suggested it would be something extra to put down on my CV lol - dont think it helped me get my placement though. Plus its nice to carry around the little card you get in your wallet ... flash it at people rofl.
Also yeah theres some good resources on their website.
Was a member last year, haven't bothered to renew membership and spent my money on SAGE membership instead.
The impression I gained (perhaps erroneously) was they seemed aimed at CIOs / non-technical managers and were rehashing topics covered months ago in other media / discussions.
That and the "you haven't renewed your subscription emails" annoyed me - if you seriously feel the need to tell an IT Professional not to email you their credit card details for subscription renewal, I don't want to be associated with the people you're letting in. :)