First A220-100 flight yesterday, MSY-LGA. We had 3C & 3D. The seat was very comfortable. We agreed that they were more comfortable than the F seats on any other narrow body in the fleet, including regionals. The legroom in Row 3 is great, Rows 1 and 2, not so. As has also been pointed out, the distance from row 3 to the first row of C+ is spacious and doesn't make you feel guilty of using full recline. The additional space between rows 2 & 3 seems to keep row 2 recline from being bothersome. The irregular seat spacing appears to be related to seat/window alignment.
We wonder why the seatbelts were the airbag style. Is that also true of rows 1 & 2?
The IFE screen is very nice but the audio was drowned out by aircraft noise using the DL supplied earphones. We didn't have any earmuff style headphones with me but they should make a BIG difference in blocking ambient noise. The power is very easy to access
As has been noted many times, the seatback storage sucks and the tablet storage is useless. The tray table was OK but it would be nice to have it extend slightly further from one's body and be supported at the non-hinge end.