I am the proud owner of a 1998 328 convertible. My mid-life crisis car, so to speak, and so much more practical than a Viper. I bought it because: it's a great car in its own right, is a no-compromise convertible, and it fits in the garage even with a refrigerator there. No, seriously, that was a factor. Lots of room inside, relatively speaking, for a small car.
The car drives and handles like a dream. As my neighbor across the street noted, "this is best car I have ever driven". It goes fast. It stops fast. It loves corners. I went for automatic and have not regretted it, but that's a personal preference.
Many user-convenience features: power everything, Harmon Kardon sound system, heated leather seats ("mmm...heated leather..."), remote/alarm system, side air bags, power convertible top. Many, many little dashboard buttons with only pictures for labels, but you get used to it after a while. Though I'm not sure how to change the date in the clock/computer.
Space is 'cozy' for me at 6', though I'm used to bigger cars. The back seats are very useable for my two boys, age 7 and 8. Note that this is not a car for someone with children under 4, since car seats would be a pain to access in back. Likewise, kids older than about 12 would be a tight squeeze. But for me it works great. I couldn't take the boys to baseball practice in a Boxster.
Looks-wise, the car is outstanding, especially with the top down. Winter-wise, it's worked out OK in Virginia, with our three snowstorms/winter. The car heats up pretty quickly. The rear wheel drive is not going to have as much traction as a FWD car, so that may be a factor much north of here.
What's not to like? A few small things. It's a little noisy even with the top up, since it's a convertible. The passenger door lock was balky at times during the winter, but is working now. The paint seems to scratch easily--my son left a scratch with the hose. Ouch.
Keep in mind that this is not a cheap car. I spent $38K for mine, buying it early in 1999 as a used vehicle. The good news is it seems to retain its value pretty well; I see ads for these cars now for maybe $35K, so even in five years I can probably sell it and not be out of pocket for something boring.
Oh, and BTW, if you are not used to BMW service, you'll be pleasantly surprised I hope. Nice dealerships, scheduled appointments, no charge for scheduled maintenance for four years. Cool!