I thought it was a big improvement on previous fires. A big explosion (I loved the reaction shots, especially at the poker night), references to the past (Tamwar's reaction was exactly right, very in character - as was Massood's) and Tosh staying calm and knowing what to do. Johnny really ought to have been in hospital, and it was shame Ian wasn't around to react to Peter coming out of the fire, but that's fairly minor.
Alfie running in and getting back out with very little damage (while Kat was - um - roasted?) was silly though. I know it suits the script that he's the hero, but it was rather ridiculous. Ricky going into a fire about twenty years ago on EE was more realistic.