Disc compatibility issues have plagued Blu-ray since the format came out. At first, we figured it was part of Blu-ray's growing pains and would eventually go away, like the annoying confusion about Blu-ray profiles. However, disc compatibility issues have persisted and manufacturers regularly have to issue firmware updates for their players when certain movies won't play.
We recently posted a review for the LG BD570 and shortly afterward we saw several user opinions complaining about playback issues on "Up"--primarily, the movie skipping ahead at 1:03. That's frustrating for us; "Up" wasn't a disc we looked at during our tests, but obviously glitchy playback is a serious issue. Our review of the BD590 is also coming soon, so we wanted to investigate.
We contacted LG about the issue (they're looking into it) and rush ordered a copy of "Up." The first time we tried to load "Up" on the BD590, the player froze and we were forced to power it off. But after that, to our surprise, the movie played fine on both the LG BD570 and BD590 on several attempts, with no chapter skips around 1:03. (We had no issues with "Terminator: Salvation," either, another disc that some found problematic.)
Considering the initial freeze-up was the only time that happened during our testing period with the BD590, it's hard to consider it a major flaw. We don't doubt that people are having trouble with playback issues, but since we don't have any firsthand evidence that the BD570/BD590 have significant playback or disc compatibility problems, we're not going to ding it in our review.
Minor hiccups are our experience--we've even had the rock-solid Oppo BDP-83 occasionally freeze on a disc--but usually they're uncommon and intermittent enough not to merit mention in the final write-up.
Ultimately, these kinds of issues are what the user opinions are for. No matter how much disc compatibility testing we do, we'd never be able to match the extensive testing that goes on just from buyers watching movies on their players. CNET's user opinions and the "owners' threads" at AVS Forum are great resources for discovering issues like this that we won't catch in our limited review periods. (But user reports aren't flawless, either; our impression after reading CNET user opinions/AVS Forum was that both LG players would definitely have problem with "Up" and that's wasn't the case with our review samples.)
In the bigger picture, it's unacceptable that disc compatibility is still an issue on Blu-ray players, when we didn't have these problems in the DVD era. Blu-ray has a lot of perks, but we'd easily trade BD-Live for perfect disc compatibility.
Update: LG has issued a statement regarding the playback problems some users are experiencing:
LG takes seriously the feedback from customers regarding sporadic BD570 and BD590 playback issues when some Blu-ray discs are viewed in the 1080p/24 mode. We are informing users that by switching the video output to the 1080p/60 mode they can avoid this issue and still enjoy Full HD1080p playback of the disc. We are working to develop a permanent solution, and will provide additional details on its release in the near future.
Additionally, we've been able to confirm the issue on our review sample with "Up" and "Terminator: Salvation". Our previous testing was only in 1080p/60, which is why we didn't notice it previously. As it stands now, we don't feel the problem is significant enough to warrant a rating decrease on either player--especially since 1080p60 playback is fine--but we'll continue to monitor user feedback to see if the issue becomes more widespread.