No worse than the Denon CEOL...
The comparison review of the Denon CEOL (RCD-N7 + speakers) made play of the wi-fi that it has over the Marantz, but given powerline ethernet is generally more reliable and doesn't require loads of Cat5.
Featurewise, the Marantz can drive 2 pairs of speakers (the CEOL can't) and can be used bi-amped to power 1 pair (for greater control) - I use this feature to drive a thumping pair of B&W DM603's and I can vouch for the sound quality. This little box replaced a 4-box Arcam Alpha rig!
The only gripe about any of the new crop of boxes featuring AirPlay is the rip-off for the firmware upgrade! Aren't you buying these boxes because of this feature? Why get charged extra?