The new recorder is thinner and lighter than its predecesser. And while Wingfield Audio didn't make many direct comparisons between the audio quality of the two devices, the review does state that the built in mics are significantly better than the mics on the PMD660 and sound almost as good as the mics on the smaller PMD620 recorder. If true, I'd say that means that under certain conditions you could record broadcast quality audio using the built in mic. With most recorders in this price range, I'd recommend finding a good plug-in microphone to use 90% of the time. But if you're in a hurry and just need to pull the recorder out of your pocket and hit the record button right away, it's good to know that you might get decent audio quality.
Wingfield also says the recording quality qas excellent when using mics that draw phantom power from the XLR inputs. Dynamic mics did not perform as well, generally producing noisy results.
Using a phantom powered mic will cut down on your battery life a bit, but Wingfield Audio says they managed to get about 5 hours of recording time from 4 AA batteries, which ain't bad.
You can pick up a Marantz PMD661 from Amazon for about $599.