They're great cars if you're willing to live with the risk of compression problems and remember never to flood the thing.. throw on a set of slight lowering springs and the handling is like a big gokart, keep the engine on song and they're extremely rapid (in 231 guise, anyway) and they're pretty handy around a track, too.
But, you have to watch for:
Compression problems - this means trouble starting when hot, flood very easily etc
Coil pack problems - if the tops of the coils are turning white they're toast, LS1 coils are a popular upgrade for ~£250 and help with potential flooding issues
Expensive spark plugs - seriously, seriously expensive spark plugs
Regular oil changes - sump oil is injected into the combustion chamber so you need to run the right type and clean oil, alternatively fit a 2-stroke oil kit which replaces the sump injection system with a reservoir of neat, clean 2 stroke oil up where the washer bottle was (and replaces it with a tiny washer bottle)
Mine needs a rebuild, but I knew that when I bought it for ~£800. A decent car should come in about £3k or buy a known bad car like mine for peanuts and then pay another ~£1200-2000 for a rebuild (less if you can do it yourself) from somewhere like Apex Rotary. Personally I'd do that as at least then you know it's not going to cork it in a short space of time!
Oh yeah, they're quite small inside so if you're particularly tall or have a fat arse like me you might find it a bit of a squeeze.