Loosely based on the exploits of Red Adair, Hellfighters is a perfect vehicle for John Wayne. The characterizations are a bit overstated, but this was standard for the era, so I allow for that. And who could have picked a more appropriate love interest for the Duke than Vera Miles as a San Francisco Department Store heiress.
I thought Jim Hutton and Katherine Ross made a good offsetting couple to JW & VM and Bruce Cabot, a long-time associate of Wayne's, an excellent comic element.
I think the thing that sold it for me was the reality of the fire scenes which I just marveled at until I saw that Red Adair was a technical adviser on the film. That and the knowledge that Wayne was all for reality as much as possible really made me a watch it anytime fan of this picture.
If one takes into account the decade in which the picture was made, it can be and is, for me at least, a very enjoyable film. I highly recommend it!