I completely disagree with M3What. The german engines are efficiently laid out, not "crammed". I'll tell you what's cramped, the V-6 in my wife's Mazda 6 and my brother's Taurus. Having to remove an intake manifold to swap spark plugs is ludicrous and what's up with all those wires running from corner to corner? From the cars I've seen under the hood, BMW has the finest bit of organization with their parts. The engines are a breeze to work on if you have the know-how (hello Bentley manual) and free time. The parts are not "very expensive" if you purchase them from somewhere other than a dealership. Online wholesalers abound and are routinely mentioned in these forums.
Also, the E46 usually has a few particular parts that go and right around a specific mileage (camshaft sensors, window regulators, batteries) so yes, expect to replace a few particular parts within the next couple years... hence budgeting about $400 per year to cover the average over that time.
With a year and a half left on the warranty, you'll probably encounter most of your typical E46 problems before it runs out.