If you read the Sony BDP-S1 Blu-ray player review, you'd have a good idea of what the Pioneer BDP-HD1 player could do. Because, strangely enough, they are identical. HDGuru found that the back panel, disc drive, menus, format support, and capabilities were exactly the same between the two players, down to the time it takes they take to boot and load a movie.
When asked, Pioneer said they manufacture the player itself, so does that mean they make Sony's as well? Is that the reason for their massive delays? Does Sony not even make their own Blu-ray players, something they've been pushing like crazy?
Hard to say. But that's the way it looks now. Fortunately for Sony, their version of the player is $1000 compared to the Pioneer's $1500. But for the extra $500 you get an ethernet port, a longer warranty, a more conventional black finish, and BD-R/RE recordable playback.
If you're looking to author your own discs or enjoy updating firmware over the net, the Pioneer seems like a better buy.