Feature:
The workmanship of the guitar is flawless, and the materials are as well. However, bone bridge pins to match the nut and saddle would've been a nice addition. It's very easy and inexpensive to do that upgrade yourself though.

Quality:
One of the best made instruments money can buy.

Value:
Considering that I'll have this guitar for the rest of my life, and then hand it down to my daughter - that's value people!

Desirability:
It's beautiful in it's artful simplicity.

Sound:
Before purchasing my D18 I tried many others. There were a few that played and felt a tiny bit better than the D18, but the sound, wow!

Ease of Use:
Not quite as easy to play as a Taylor in the same class. But it still plays exceptionally well compared to any other guitar on the market. Again, the sound has no close second that I've heard. If you're at that level where you're considering a guitar in this league, then sound is probably everything to you.

Support:
It's hard to imagine a better warranty than lifetime!

Overall:
The Martin D18, for me, is a lifetime investment.