I've owned my 330Ci for just over a year now. My previous car history has been a Subaru Liberty (4th Gen 3.0), a BMW 135i ('09 E82), and a Mazda MX-5 ('99 NB8A), with each being manual. The MX-5 lasted me four years but needed some more space, and considering I'd almost gotten an E46 for my first car, I was bound to inevitably come full circle and get one. After looking for a few weeks, with the only conditions that it be a 330, coupe and manual, which is a difficult task, because while there's always more than 80 automatic 330's for sale at any one time, you'd be lucky to see 8 manual ones for sale.
I bought this car (sight unseen) from interstate, flew up and drove it 1000km back home - without skipping a beat, so first test was all good. Wouldn't do it again as there were a few niggles I would have liked to have known about before buying. After watching the market for months afterwards, I didn't see anything I liked better come along, so I have no buyer's remorse in that regard.
For me the E46 looks timeless. it's perfectly proportioned and it still holds up well almost two decades later. It's been lowered on coilovers and I picked up some BBS wheels to run as well, which complement it perfectly. A previous owner has put on a replica M3 bumper which adds to the looks.
The interior of this car just feels right, it's aged just enough to get character yet still look modern enough, and I much prefer it to the E90/E82 which followed. Full electric adjustable sports seats, leather everywhere and a decent driving position all get ticks from me. Some of the seat stitching has come apart with age and the B/C pillars need re-trimming, but they're small DIY tasks for a rainy weekend. The audio system has been fully upgraded and there are plenty of direct plug-in aftermarket options as far as head units go. Rear seats and boot has enough space for most things that I'd have to deal with, even to the point of easily folding down the seats to fit a bike in there.
170kW/300Nm is, in my opinion, plenty fast enough for most regular driving, whether city or highway. I've driven and been in plenty of cars much faster than this but unless you're on a racetrack, they just get to a level of being fast point-and-shoot missiles you just hold onto and feel less connected actually driving with. (Clearly some of the MX-5 driving feel still shapes what I enjoy!)
The 330Ci has enough torque down low to motor around with no problem, and plenty of get up and go at higher revs. Fuel consumption is reasonable - maybe 7-8 litres per 100 kilometres on highway and 12-14 around town, but I don't put enough kilometres on it to worry or track it closely.
Some owners swap diff ratios to get a bit more acceleration but other than that there's nothing really cost-effective worth doing to get lots more power out of these engines. The M54 won plenty of awards in it's time for being a brilliant engine and whilst almost everything these days is shifting towards turbo 4s and smaller, nothing is quite the same as revving out a solid BMW inline 6.
If you're not mechanically handy then owning one of these will be expensive. If you know your way around a toolbox and a YouTube video or two then there really isn't anything scary about them - you can find every resource and how-to guide you'd ever need. Genuine parts can be expensive but there's also plenty of other options. Control arm bushings, cooling system etc. all wear out over time and need replacing as you'd expect, and the rear subframe cracking is probably one of the biggest-reported issues with E46s, however if it's been fixed and reinforced then there shouldn't be any further problems.
Yes, a lot of E46s have likely had some young male owners and a bit of hooning in their lifetimes, and you won't find perfect examples. Look for one with some history, definitely inspect it, hold out for a manual one (and 6-cylinder), budget a couple of thousand a year in maintenance/fixing things, and I promise you you won't regret it for the all-round driving experience it brings. For the $12k i spent buying this, I'm confident I could sell it tomorrow for that again, so depreciation-free motoring always wins points in my book. Whilst it's not an E46 M3 - picking up a manual one of them will set you back three, four or even five times the cost, and unless you're using it to its fullest potential, for 95% of people that much of a jump just doesn't seem worth it to me.