Jens Kutilek

It’s tricky. Nearly all of the aspects mentioned here can be intentionally done differently and still make a good font.

E.g. FF Trixie, the original distressed typewriter font.

• Quality of glyph outlines = horrible
• Quality of spacing = monospaced, what do you expect?
• Quality of kerning = kerning is nonexistent

The font would fail by these criteria, still it is an important milestone for OpenType fonts.

Not to say that quality criteria don’t matter, but it’s the old saying, if you know the rules you can break them.

In my opinion, ligatures and alternates are overrated. Type designers (including myself) can get carried away adding them. Most users will never find the alternates. Ligatures (esp. ones that are active by default) can do more harm than good if they are added to designs that don’t really need them.

Maybe http://fontdrop.viktornuebel.com is helpful. It's a web service, so no installation required.

Another web tool is http://www.alphabet-type.com/tools/charset-checker/ but it may be too complex for the casual user.

There's also a Python BDF module. I haven't used it myself, though.

I filed an issue regarding the TrueType conversion on GitHub.

Well I noticed the bumpy curves by zooming in on the PDF specimen, which was the reason to compare the outlines on top of each other in the first place.

I agree that at the intended environment and size it will not be noticeable. But you never know how large somebody will mis-use a text font