I guess it depends on how you want to use it. I just compared the internals on my Zoom with the internals on my Marantz PMD620. The Zoom sounds better, in my opinion. Mic-in and line-in may be a different story, however. The mic input on the Zoom is noisy and the Marantz sounded much better. I have yet to test line-in, as I am waiting on a pre-amp...
There are a million threads relating to the R09 on here; you should probably take a look. And the sites listed by sailcat (above) are good for Zoom info...