I run in mixed mode because I have a Slingbox with a DLink "g" Ethernet to wireless bridge and a DLink "g" wireless internet camera, as well as a wireless HP printer/fax/scan "g" device. I also run an ancient Pentium III with a DLink Draft N wireless PCMCIA card and my SR 2.4 MBP off this router.
Overall, I'd give it a 6-7/10. My results with Mac OS X are similar to that posted in the other relevant thread the link for which is posted above. I have not updated my router firmware to 1.03, but need to do so.
Frankly, for the first 6 weeks I owned the thing, it constantly dropped Internet connection and/or the wireless devices above would lose signal from the router. I went for a 7-10d period having to cold reset the thing at least once a day. Finally, I lost internet altogether. When I disconnected the router from my modem and hooked the modem directly to my desktop, my internet was fine. I then called DLink and basically ended up reinstalling all the drivers and cold resetting my modem and the router. For now, it basically drops signal every few days but recovers on its own without need for a cold reset. Stability seems to be an issue.
Frankly, I went with DLink because the wireless webcam I wanted was DLink, and since I figured that would be the device most likely to give me problems, I thought it would be wise to keep everything else DLink. I got a good price on the DIR-655, so went with that one.