So what's so special about a 606?

After about 1 1/4 year of owning a 1999 E300TD here are some impressions:

My first diesel and I am really impressed by the acceleration from a stand still and from 30 to 100.

The car has annoying electrical and dashboard problems like low oil level, lamp out etc...

This car only gets about 28 mpg but it's my wife's daily ride, all highway.

I think it handles extremley well in corners.

Mass air flow sensor, glow plugs, rear window motor all replaced.

No sound insulation in the roof, I can hear the cables in the headliner moving around (black car)

Is the 606 engine very different from the tried and true MB diesels and would one consider this car a collectors car?