I have complimentary membership being one it's first members and helped with the initial testing of it as a user.
I find it excellent - very easy to search for either One World or Star Alliance award flights. If you're only a member of the BAEC though it may be just as easy to search on BA.com - to look for flights other than on BA change the search to 'include our partners'
I've also been a BA member possibly for nearly as long as you but I've found loads of availability to almost anywhere I've wanted to go including 3 times to SFO in First.
Do remember that it's not really worth using your miles to fly in economy long haul on BA and also that you need to plan well in advance.