Aspects of quality for a typeface

I've been thinking on this today, and I've quickly written up a few things that I find to be the main points that make a typeface of quality. I would love to know if anyone has something to add to this list. 

I feel like I lose site of a lot of these overarching themes when I'm in drawing mode, so I'm trying to make a comprehensive list of things to think about so I can constantly be assessing them while I'm drawing. Any additional thoughts would be appreciated!

• concept 
• does it solve a problem? 
• who will use it? 
• why are you making it?

quality of drawing

• individual glyphs are drawn well

spacing

• do the negative and positive shapes harmonize with each other?

features

• does it have interesting alternates & ligatures?

expansiveness

• How many weights does it have? 
• does it have alternate styles?