Firstly, why not take a trip to Euston and have a run to MK and decide for yourself otherwise you are making judgement based on opinion. That said I will however happily give you mine which you are free to agree with or disagree with as you see fit:
They are crap.
The seats are awful: Thin, narrow and seemingly designed to cut of circulation. After about 90 minutes they are uncomfortable in my view. The leg room seems poor, certainly beneath one of the few tables. The window frame seems to intrude into your sitting space and be designed in such a way that you can’t, comfortably, rest your arm in the gap!
There is a dearth of plugs in standard class ( perhaps because there construction straddled the period between on train radio and mobile/tablet devices?) far too many of the seats offer you a view of white plastic land and the lighting is dingy, dark and cave like while the colours used inside do nothing to brighten things up. The amount of natural light allowed in through the vision slits is terrible and the whole carriage always seems dingy ( yet the ones in Europe aren’t!) There is no luggage room, the overhead rack is a joke & they also seem disproportionately noisy!
I am certain for the TOC a pendolino is a fantastic machine. Quick, speedy, reliable, cheaper to run, easier to maintain, easier to operate, easier to timetable etc etc. However in all of this wondrous progress the designers forgot one element: passenger comfort!
Now I am sure the moderistas, especially those with little experience of travelling on a real train or in standard class, will be along soon to mock the rest of us for our dinosaur like views and explain how fantastic a pendo really is.
Decide for yourself.