Long term member
Been a member since 1995 initially through the RAF as full time and now since I became a FISO as an associate memebr at £5per month. Have used travel perks a couple of times. The fact that they provide legal backing is a plus, a co-controller in RAF used this facilty to his advantage many years ago - but probably wouldn't have benn able to afford it with the membership.
So yes I woould recommend joining, you can offset against income tax as membership of a professional body.