Hmmm - I think those basing it purely as a 'stunt episode' have the wrong idea. The story isn't about how big the explosion is, it's about the aftermath for Kat & Alfie / Tamwar possibly
..... that said, I felt like the pacing of the episode was pretty off. Half the episode was dedicated to the buildup and boring Sharon dialogue and then we barely saw any of the actual fire which I thought was pretty disappointing.
Overall I'd say the story line looks very decent, but the actual episode was pretty forgettable considering the hype. Rightly or wrongly, viewers tune into a fire episode because they want the tension and the drama - which I felt lacked pretty severely.