I've used two DVD players since 2000 in my system, replacing and selling an Arcam Alpha 8SE at that time because, in my system the DVD players either equalled or outperformed it. And, of course, at a substantially lower price.
The first player was an RCA 5223P and the player I use currently is a Panasonic S47. The prime weaknesses in mass market DVD players are a) cheap power supplies and b) flimsy build quality. My experience is that if you find the right DVD player and address these issues inexpensive DVD players are capable of decent performance.
I may not have gone the DVD player route if my system did not already have good power/line conditioning; I use an Inouye line conditioner. I found that the DVD players, with their lower quality power supplies, benefited greatly from line conditioning and, for example, a good power cord. I use cryoed DH Labs DIY cords terminated with Marinco ends. The Arcam, for example, while it benefited from line conditioning and power cord upgrades, did not benefit nearly as much as the DVD players.
With respect to build quality/flimsiness, there are a number of very cost effective ways to tweak lower priced players to enhanace their performance: 3M damping sheets or dynamat, rope caulk used internally on the transport, decent quality support feet, etc. all of which I've done.
The problem with mass market players is that they (and quite possibly their parts) are constantly changing every 6 months or so, so what might be great today (or even tomorrow on the line depending on parts availablity) may not be particularly great in 6 months with the replacement model. But find the right inexpensive DVD player (I'm certainly not saying they all sound alike or are capable of good or great sound), take care of resonance issues and power issues and mass market players are capable of decent performance. Nowhere is the law of diminishing returns higher than in digital playback.
