I think the lighting and general ambience on the 701 is something that they've managed to do really well, and should be praised, especially in comparrison to other new fleets we've seen recently
It doesn't feel clinical and blinding like on many modern trains such as the Desiro Cities, nor does it cast shadows. It brings a more airy, natural feel, while still managing to be bright, yet at the same time not feel jarring. A lot of this is down to the positioning of the lighting fittings, being placed on two sides of the roof, rather than a large centre module, meaning it has the chance to spread more naturally.
These also feature diffusers, which for comparison 700/707/717 don't.
Additionally, the choice of wall colour, being grey, rather than white goes a long way to make the ambience more pleasant and less harsh. This is, interestingly, the only Aventra in the fleet to feature this other than the 345, with the 710, 730 and 720 all featuring white walls.