Travelling to-and-fro Stansted by train was awful compared to taking the National Express up to the airport. The CrossCountry trains were small and crammed to the brim, I had even less leg space in the train than I did with my budget airline flight. Even sitting up completely straight, I still felt my knees rub up against the metal of the seat in front of me. The train stations and trains themselves were filthy with trash lying around. One thing that always bothers me while travelling in the UK, is how there's essentially no cell service along the whole route. You're lucky if you even get to pull up HN reliably.
I suppose it helps travelling first class - but that is not at all realistic for most people living in the UK.