T5 is a bit pants. I flew out of there on Friday, still waiting for my luggage which I'm informed is at Heathrow and will be sent at some point. This is immensely useful, I have made sure I keep 'some point' free in my diary so I can receive it.
It's nice that it's big and airy with lots of light, but it crap that 99% of the shops are unhelpful stufff like Harrods, Cartier, Gordon bleedin' Ramsays. Very few normal places to eat food. There are two bars, both too small. Some of the gates are right in the middle of the shopping part which is annoying. And I dunno whether it was just 'cause it new or a permanent arrangement but they don't seem to tell you which gate to go to until half hour before the take-off, and some of the gates are 20 mins away.
Check in and security were very quick, but this may be because there seemed to be hardly anyone there. Or it maybe be because it's so big it seems that there was hardly anyone there. Or it maybe something else.