Will it include a 3.5mm or 2.5mm headset jack for plugging in a standard headset? There are very few (if any) reliable and well-designed cordless landline phones that also provide a headset jack for true hands-free use when away from the base station.
Is this solely a land-line phone or will it be VoIP capable? I'd suggest that it leverage the SIP protocol and support G.722-based HDVoice, which is part of the DECT/CATiq standard. That would make it competitive with the likes of the Gigaset range, which are at a similar price point.