I used T5 for the first time a few months ago and it was fantastic. Clean, bright, quiet.
I used T5 for the second time this week, and now it's full, it looks and feels like a slightly newer LHR terminal. It was dirty, busy, hot, long queues at 'Fast Track' security, the BA Galleries Lounge (South) was untidy, litter abounded and there didn't seem to be many power points to plug the laptop into.
Not that impressed really.