Sure, I was also wowed by T4.
It didn't take long for my opinion to change. Only had to look at the direction arrows towards my gate that prepared me for a 22-minute journey from security to the T4S gate!
So I'm afraid that the fantastic form did come at the expense of functionality; at least to a certain degree (we don't always have the luxury of spending 3 hours at the airport).

Barring a serious mistake fare, I won't be seeing LHR T5 from the inside for the next couple of years at least, so obviously I can't compare them!