I've also got a 2550 and its very good, although its not perfect.
Firstly it takes a very long time to read discs, that as such isnt a prob as it give me time to lower my screen but it does have you standing there watching the display wondering whats happening or whether theres a RCE problem.
Secondly, the layer change on mine is very noticable. Both these issues may be to do with the multiregion firmware, I think theres more than one type.
Also, and this is a minor issue really, is the backlight remote which is a very good idea, unfortunately it illuminates the buttons but you still cant see what each button does. This is compounded by the pause and the useful dimmer button being well hidden.
I am still very pleased with it and playback is noticably better than my Tosh 220e player & Philips DVDR70 recorder (no suprise there

) and I'd still buy one now.
I would like a less obvious layer change but there are lot worse playback problems out there suffered by other machines that would annoy me more.