One of the first things I did when I got my Sony PCM-D50 recorder was put it through the paces (quickly) and write up as thorough a review as I could without having spent months with the recorder. Mark Nelson at O'Reilly Digital Media took another route and spent a month with his review unit before writing up his thoughts.
We both reached pretty much the same conclusion: You'll be hard pressed to find another recorder for under $500 that's as versatile as the PCM-D50.
That said, Nelson did discover a thing or two that I had originally missed. First, the reason Sony included a 2GB file size limit is because Sony wanted to use the original Microsoft WAV specifications. While newer devices let you record a single track up to 4GB or larger, some older computers might not recognize those files. And second, the limiter feature is even cooler than I'd originally thought. The PCM-D50 is always recording two tracks, one at your set volume and another 20db lower. When a loud sound comes across as overmodulated, the recorder switches to the lower track, but it will actually boost the volume so that you really shouldn't notice any change at all. I think the reason this didn't come across in my sample recordings is because I tested the limiter by making sounds so loud that there was clipping on both the original track and on the safety track.
Nelson did have some issues with the menu layout and he doesn't seem to have tried plugging in an external microphone. And the truth is, no matter how good your digital audio recorder is, your recordings are always only going to be as good as your mic. With an EV-RE50 mic, I think the PCM-D50 sounds excellent. But Graham Riches left some comments on another BradLinder.net blog post that suggest different results using a Rode NTG2 mic. Personally I think the recorder sounds great with my external mic and I almost never use the built-in mics which are too sensitive to wind and background noise. When using my old Zoom H4 recorder, the opposite was true. I'd only use the built-in mics because the preamps were way too noisy when using external mics.
Anyway, here's what Riches had to say: