I think that you're making the right decision. I don't know what your 'mission' is, but assuming that you just want a simple aircraft that will carry 3-4 people a reasonable distance at a reasonable speed, the 172 should work out fine. Of course, if you want something fancy with retractable undercarriage, c/s prop, etc., then the 172 won't suit; but you already know that.
When buying into a syndicate, I would be concerned about the overall condition of the aircraft, its general availability, and my compatibility with the other syndicate members. It sounds as though you're okay on those points, so I vote yes.
Two things are beyond debate: (1) the 172 is relatively easy and cheap to maintain; and (2) the 172 is a definite 'name brand' and if you decide to sell your share, it should be fairly easy to find a willing buyer [let's hope that you will be happy with the 'plane and the syndicate, but it's good 'insurance'].
P.S. Here is a link that you should read:
http://home.tampabay.rr.com/flyer/owner.htm