1) Make sure you get on with the rest of the syndicate. That's essential for everything to run smoothly. If you get a bad "gut reaction" to any of them then walk away.
2) Are they charging themselves enough. Buying into a cheap share with cheap outgoings is a false economy - it just means you're going to get hit with a big bill sometime down the road. If it's flown "dry" (you pay for the fuel, you also pay an hourly rate) then this isn't so much of a problem. However, with fuel prices going up you want to make sure that, if you're charged a "wet" rate, that this encompasses, fuel, maintenance, and engine fund.
If you're happy with the above then do it. You may not get much of a reduction in the hourly cost once you take into account monthly standing charges, but being able to go places at will more than makes up for that
