The digipaks I've seen make it easier to see the cover art than through jewel cases, especially if you're in an area/room with uneven light distribution and glare. Although, there is something to be said about the somewhat shinny look of cover art in a jewel case for certain types of music - ie., music that would be comparable to the content of certain glossy magazines.
I've never bought a new CD with a broken digipak tray, however, some spindles in one of the trays for my Herbie Hancock
The Complete Blue Note Sixties Sessions were broken when I bought it used - not a single CD digipak, though. But I would say all of the digipaks I've bought were externally imperfect in some way, to some degree, usually a slightly dented corner - this is before I've even handled the CD or transported it. The only consistant exception has been the JVC XRCD cases, which are little hard cover books and are very pricey. But even with jewel cases, I've never bought a perfect case without some minor sratches if you look closely. And sometimes you'll get a case of a CD you ordered online with an obvious crack(s), although this has been rare with me.
I don't have much experience with digipaks with cardboard/paper slots or mini-LP cases, but I will give some props to the mini-LP case that comes with the Coltrane
Giant Steps Rhino re-issue (I think there are the same/ similar presentations in other Rhino Jazz re-issues): The cardboard case that is supposed to resemble an LP cover is rigid and with the slot angled so that the CD has not become very scratched for me. I've had this CD for about five years, and have played it many times, but the CD plays and looks fine, even in comparison to similarly old/handled jewel case CDs I have. The mini-LP case is also a clear facsimile of the original LP cover, although with an album as relatively popular as
Giant Steps, I'm sure they had many samples to choose from (some of the RVG re-issues, for example, look like straight transfers of aged Blue Note LP covers without any digital manipulation). The original liner notes on the back of the
Giant Steps mini-LP case are readable, although it might be easier to read them in the booklet (bigger print), but you wouldn't have as much of the old-school effect of seeing the back of an LP cover. But, in the end, it is kind of awkward to remove the CD from the case.
In general (from my experience), I think the jewel case wins in durability and practicality (including easier to open and remove the CD), but is not as aesthetically pleasing, but, as always, this is not always the case between any two albums/compilations you could find, or any two people. The meaning of the Digipak should be contemplated by all music lovers! - more so than a thread that says: 'Amp X has landed.' IMO, of course.