A lot of the time, I wish I didn't even know about the existence of ligatures.
At least with the fi/fl/ffl/ffi/ff ligatures, most of my life, I didn't even notice they were there when they were there, and didn't notice when they were gone. It's only when I started investigating why it is I found LaTeX output subtly better than MS Word output without really realizing why that I learned about such things.
Now of course, I'm cursed to noticing
both their presence
and their absence, and both are little distracting. Good typography of course is invisible typography, and normally it would be--I've basically made by own book reading experience worse by picking at it.
Generally, however, I think the inclusion of ligatures looks nice, but there is one exception: I've noticed that a lot of "Pro" fonts like Adobe Garamond Pro and Minion Pro, etc., have "Th" ligatures, which for some reason, just seem over the top to me.
