I can't think of anyone in my company that is a member. If they are, they're very shy about it! I did try joining myself some time back, but my lack of 'sponsors' (i.e. you have to know two members who will vouch for you) put the kibosh on that! I'm not feeling seriously disadvantaged by lack of membership.
If you want the letters after your name, go for it - if you can find the sponsors. If you're after serious discussion of the meatier topics in aviation, or career advice, then Pprune's a much better (and cheaper) resource!
Scroggs