Others already posted they are great and reliable cars as long as they are maintained. Area's of concerns are in the front seals, timing belts, balance shaft belts. These require replacement about every 30k miles. Fairly easy to do.
Other maint area of concern is clutch replacement. Very expensive to have done and tedious to do for the home Mechanics. 944 N/A can cost up to $2k or more depending on where you live. Turbo cars can cost up to $3k. It's mainly due to complexity of what needs to be removed to change the clutch. Clutch is located behind the eng and transaxle is at the rear.
If both areas have been addressed than you have a good car.
944s is an odd model of the bunch. Yes it is the 1st 944 with 16 valve but perf is not much improvement over the regular 944. Not many 944s out there.
My choice would be the 944 S2. Makes a great track or street car. Has better power and tq over the 944s.
Turbo is a different animal from all 944's but is is my choice of the group. I've owned one since 1993. 1st was a 87 turbo which I owned for 10 years. great car.
Power? How much do you want is the question. Turbo lag is something to get used to.
I currently own a 88 turbo S.
Go to Rennlist and the members there will tell you all about their beloved 944. I also post there.
Here's my collection.
https://picasaweb.google.com/cas951s/Porsches
https://picasaweb.google.com/cas951s/TopDown