OP,
I've built several of the new tool Airfix kits, all in 1/48, and my experiences have been mixed. All were good in terms of detail, but fit was hit and miss. Here is a brief rundown:
Boulton Paul Defiant
Excellent fit, easily as good as Tamiya. Very good detail, and all aroung great kit of an interesting and somewhat unusual subject. Highly recommended.
Hurricane Tropical
Also very good in terms of both fit and detail. The only small issue was that the canopy needed a little work to fit properly. Otherwise great.
P-40 (Pearl Harbor version)
Very good detail, but lots of fit issues. Fuselage halves were warped and splayed out near the tail, very noticeable gaps at the wing root, the protusions on the leading edge of the wing fit terribly, etc. Every step of the build required lots of sanding, fitting, re-fitting, putty, etc. I understand that nothing is perfect, but this was far worse than what I expect from a new tool, newly engineered kit.
I have the Mk 1 Spitfire, Armstrong Whitworth Whitely, Sea Hurricane and Stuka in the stash. We'll see how they go.
I have also built a few of the new tool 1/72 kits, and some were OK while others had poor fit. None were great.
It seems that while the level of detail is consistently very good, the quality of engineering is inconsistent with Airfix.