I must admit, I’m more impressed with the LNER IETs over the GWR ones, though I’ve only had one trip on the latter.
After a few ‘positioning moves’ while chasing the 91s, I don’t find them that bad to travel on.
Interior is more welcoming and warm than the GWR kind, and the seats feel slightly comfier.
Seats if you’re sat upright are quite comfortable, and plenty of leg room, though this is for a max 50 minute journey, and don’t sit on your wallet!
Luggage space as other posters have mentioned seems too low, though I rarely travel on that route with more than a small bag.
My only complaint is the air con seems far to warm most of the time.
My dad on the other hand who travels regularly in first, and has recently gone from 9 car to 2x5, has mentioned that the ride is awful at the front of the rear unit, but fine at the very front.
I think after they bed in they will be a good replacement, however for LNER, it’s worrying how many 5 cars have been ordered. I understand it for the Lincoln services and those extending further than Leeds, but they aren’t the bulk of the trains run.