This has been asked a few times,and i think its worth it...the mags a good read,and u get good discounts off servicing/parts 10-20% or more,plus the chance to go to some of your local club meets,which can be qt good.
I saved £300 IN MY 1ST 2 YRS,having had discounts on my servc,a bmw strutbrace,and a faulty wiper assembly,that bmw were only going to pay 50% of,til i pushed my club membership and said it was worth upto 50% discnt on parts...so i have had my moneys worth...plus i always enjoy reading the mag(and they even did a mag article on a z4-forum meet,and Donated a free membership ,to our Raffle draw
I am a member. Haven't had the opportunity to use the discount, but the monthly magazine is great, and I like supporting the cause. If you sign up for a couple (3?) years, you get a cool BMWCC grill badge (at least with BMWCCA) - I have mine in the garage....
Good mag and very nice when you win a year's free membership i will renew next year as the mag alone is worth it also they seem to run some good trackdays if that's your thing, oh and there's a nice sticker for the window