Pilot did a Buyers Guide for the AA5 in the June 2009 edition, concentrating mainly on the Cheetah; you can probably get a re-print from them to get a bit more detail.
The main things to bear in mind seem to be the bonding issues previously mentioned, checking the nose leg and firewall for landing abuse and the main spar which is lifed at 12,500hrs. Not a big problem, but taxiing with a castoring nosewheel and differential braking takes a bit of getting used to after steerable nosewheel aircraft and needs to be borne in mind with crosswinds. The sliding canopy is my favourite bit; you don't get fried on the ground in the summer, it offers good visibility and easy access.