Hey SLK2C230K-
I had a '99 323i 4-door with the sport package and manual transmission. I bought it 8 months ago, used, with 36,000 miles. It had decent power with the manual, but I hear that the auto transmission on those cars saps a lot of the power.
It didn't have the premium package, and it disappointed me that without that pricey option this already expensive car didn't come with small details like lights in the visor mirrors, map lights, temperature display, or an interior trunk release, among other things. Most are things that other manufacturers like Honda make standard on their cars, and things that people always noticed weren't there when they got into my car for any length of time.
The leather interior didn't wear very well- this is a known problem with the E46s, they have a lower-grade leather than other BMWs and they show wear very quickly.
Besides that, I was turned off by the number of times I had to visit my dealer for problems- mostly minor ones like the windows rattling like crazy against the rubber seals (even after numerous trips to the service department). All in all, I had 8 trips to the dealer in 7 months.
Then, a few weeks ago, a truck ran me off the road and totaled the car. I heard about the $5000 off MSRP deal that Mercedes was offering on the C230, and after driving it, the decision was easy! 8)