Normal mapping - is it worth it?

Yes - if done properly. But because Blitz3D's support for normal maps is limited and hard to use, most users don't get very good results. Unless Blitz3D gets tangent space normal maps someday I wouldn't bother... object / world space normal maps are good for static stuff only.

I could show you how I used 1.4 million polygon model made by me for generating / baking normal maps to a 6000 triangle model - the results were amazing, partly because our (metallic) shaders were good and whole thing was HDR. But since that's work stuff, I can't show that, sorry. But believe me: normal maps are good, Blitz3D just might not have the muscle to use them properly.