I use this device to record myself playing harp and it works great. Clean sound, easy to use interface, solid construction, easy navigation. 4 stars because it's not perfect (see my observations below).
I did a lot of research before I bought this recorder and the reviews I found comparing the DR-2D with other top recorders like the LS-10/11, Sony PCM-M10, Zoom H4n were more favorable to the mic quality of this one. I am satisfied with the mic quality.
I compared this recorder side-by-side with the DR-05. The buttons of the DR-05 are bigger and considerably easier to use, but the DR-2D is not bad. The wheel helps, mainly because the DR-2D has many more functions, but is not as good as DR-05's big and solid buttons. I loved the simplicity of the DR-05, but given that the internal mic of this one is better, I preferred the DR-2D.
The buttons of the DR-2D are tiny, but I got used to them.
If you're planning to buy an AC adapter, I bought a Sony PSP 1000 adapter and it works fine. The Tascam adapter costs twice as much. Both are 5V, 2A.
(By the way, kudos to the Sony adapter, I use one on my 2wire AT&T modem after the original died, which seems to be a known problem for this modem.)
A few observations that might help novices like me:
1. All the recorders I used (Zoom H2, Tascam DR-05 and this) record my harp with clean sound, but at very low level (with mid to high mic gain even). I always need to normalize using Audacity to get a volume level comparable to mp3's I have (and it sounds great). Not a flaw, just an observation. I think these recorders are made to record high volume like a full band playing, and acoustic instruments are recorded at low volume. Interestingly, the output is high enough when played from the device itself, in all cases.
2. Mic placement makes an enormous difference. I use this recorder on a $20, light-weight, Polaroid tripod that you can buy from Amazon and it works great. Then I tested many positions until I found which give the best recording.
3. You will probably not find the perfect recorder. I like the DR-2D because of the mic quality, possibility of recording true 2 channel (2 independent files), solid construction, comes with a remote. But I wish the buttons were fantastic as DR-05's, for example. I need 3 buttons clicks to delete a file in the DR-05, and 6 on the DR-2D. Or, as another reviewers said, I wish I could bookmark different sets of gain/sensitivity, etc. Mic sensitivity and volume have dedicated buttons on the side that sometimes I like, sometimes I prefer the DR-05 way. And all this is subjective. So try not to lose your mind doing your research...