Good to drive I think, only had a go in one once. Bear in mind the engine on a Boxster is completely concealed and some of the service items are very time consuming/expensive, so there's always a risk that they have been skipped. If it's had a full Porsche dealer history then it may be worth considering, but at this stage in its life you're basically looking at the first major failure writing the car off. Might happen in a week, might never happen!
Check out honest john, as ever:
What to Watch Out For
Must have fully stamped up Porsche dealer or Porsche specialist service history, preferably itemised bills as well.
Cracked bore liners, often on No 6, can lead to total and catastrophic engine failure. First four year's production can also suffer from porous engine blocks. The first most owners know of this is overheating. Difficult to check for emulsified oil which would be an early sign of the problem. Seems to only affect pre-2001 MY cars. Timing chain/belt tensioner problems reported.
Any mayonnaise-like emulsion or scum in the radiator header tank or under the oil filler cap, don't touch the car. It probably needs a new engine. (Difficult to check with a Boxster because oil and water fillers are remote and engine cover cannot easily be removed.)
SSE