This may be too small to qualify, but Redhill's platform 0 has been very poor. It is badly-designed, and was the result of a half-baked scheme which could have achieved so much more if it had been funded properly. The signalling and junction alterations to permit all platforms to be through ones could not be afforded so we now have a sub-optimal layout, with platform 1 a 10 car bay. The new platform itself has a ridiculously short canopy, and, for the want of a simple 2/3car stopping board, all GWR trains stop at the GTR 4/5car board, outside the canopy and a long way from the exit, meaning passengers get wet, have to walk far further than necessary and are more likely to miss connections. There is also not a single poster frame on the platform, so posters are taped to cabinets, etc!
The train indicators on p0 are placed in very poor positions such that passengers are simply not provided with the information they need where they need it. For example, passengers coming up the stairs to the platform are presented with a screen listing all trains from the whole station, when what they really need is confirmation of the next train from p0. I've witnessed people trying to establish from the long list of all departures if the GWR train they can see way down the platform is the one they want, only for it to leave without them! Conversely, passengers arriving by train at the platform have to go towards the exit and turn round (it faces away from the platform) to read that same screen for their connections, causing obstructions in the process!
Some GWR trains are diagrammed to use platform 0, even though nothing is scheduled at platform 1 at those times, meaning a needless change of platform for the many people needing to change trains to those using p2 (to London), when a cross-platform interchange would be easily achievable.
In short, the under-funded project has been designed purely from an operator's (and an 'armchair' operator at that!) viewpoint, rather than including the passengers' needs properly. When I've raised the issues with GTR, they aren't interested even in the tiny things like the 2/3car stop board, let alone the bigger design failings. GWR simply say it's GTR's station and they can do nothing, which is clearly nonsense as they could easily ask GTR to consider improvements which would cost almost nothing. Privatised silo thinking has meant GTR has looked after itself and ignored the 'irritant' of GWR!