More cramped than a 737/320 - the 6-across arrangement used by BA means narrower seats than the mainline aircraft. Window seats especially so if you're tall, as the curvature of the fuselage runs into your shoulders.
Note that it's 3+2, not 2+3 in CE, unlike mainline.
I quite like the 2+2 seats at the back of Y, where the plane narrows.
It's odd to see these aircraft doing LCY-AMS - back when I started doing my regular LON-AMS commute in 2001, the ARJs were in full swing on LGW-AMS, still from that grubby little pier in the South Terminal...