Welcome Shaun, my experience has been fantastic albeit mine being a later series car. I came back to Morgan ownership after many years peddling a Caterham around and have a good friend with both a S1 and a SS Coupe. Much as with James's experience, my wife loves the Aero after hating the 7. Everybody seems to love the Aero too, every trip out brings appreciative comments and discussions.
They are fantastic grand tourers and swallow up the miles, in relative comfort. You have a "usually" sound hood, electric windows, air con, a boot and a wonderful soundtrack - what's not to like. The engine and drivetrain is pretty strong, designed for a heavier vehicle. A S1 will now be headed for 20 years old, so expect some issues with various parts and the Factory I believe don't now stock all of the parts. Though there are a number of independent companies who source or remanufacture many of these bits.
I'm not sure where you are based, but as Will suggests, I would talking to your nearest dealer(s) about the pros and cons of ownership. They often will know of good cars that may be available as well.
They are not perfect by a long way, but I wouldn't swap it for anything else.
