The actual platform area at Euston is a bit drab, but on the whole the station is perfectly functional. The only real problem is the concourse and the chaos whenever a platform is announced.
The lower level at King's Cross is also a bit labyrinthine, I seem to always come out at the wrong exit if I'm trying to get out, rather than to the NR trains.
St Pancras is now shiny, but the layout is unhelpful. Probably not much that can be done about that though.
Aside from Paddington, Victoria and Liverpool Street (which are fine, broadly speaking), I've not used the others enough to comment.
The lower level at King's Cross is also a bit labyrinthine, I seem to always come out at the wrong exit if I'm trying to get out, rather than to the NR trains.
St Pancras is now shiny, but the layout is unhelpful. Probably not much that can be done about that though.
Aside from Paddington, Victoria and Liverpool Street (which are fine, broadly speaking), I've not used the others enough to comment.
)and ECML in last few days