DR JMK,
Some preliminary findings.
The only one of my mags that had a review of the Samsung BD-UP5000 had a preproduction model which they did give initial very positive feelings about though there were some problems which Samsung convinced them would be worked out before shipping the finished model.
According to user reviews I've read, some of those caveats have not been fully addressed yet including not being able to decode the latest HD audio formats: Dolby TrueHD and DTS-HD Master Audio. True, there could be firmware upgrades that solve these problems, but none are on the horizon as of yet. There were some sound sync issues, too, that some folks had (including the original reviewer).
Nothing whatsoever wrong with the picture quality playing either HD source or regular DVDs, but those glaring audio shortcoming would make me wait for either definite firmware solutions before buying or simply waiting for a later model (if Samsung does a later model).