'99 is a great year. I have 5 of them.
Early enough to have the better IMS bearing, late enough to have the production bugs sorted on them.
It sounds like a good example. Don't get wrapped up in forum hype about what can go wrong or why someone doesn't like them, or an S model is better (I have two of them, they're not) or a tip transmission isn't cool.
For every whiny story you read about the 986, I'll give you three positive ones back.
Two weeks ago I pulled one of my '99s out of the shop where it's been sitting covered in dust (ask Jon - 78F350, about the dust.

). I washed it, checked the fluid and tires, filled it with gas and took off on a 1,500 mile round trip to Colorado for a week. It never even thought about skipping a beat.
When you get it, maintain it, take care of it, don't be afraid to drive it hard once in awhile and enjoy your new Boxster! :dance:
BTW - my 996? It's a '99 too!