^ 'To Dream in the City of Sorrows' is also considered 100% canon. No "essentially" about it. JMS says so right there in the foreword.
'The Shadow Within' is in a bit of a grey area. Near as I can tell all the Morden/Anna/Icarus stuff is totally canon and is directly referenced in the techno-mage book (by the same author) but the Sheridan/Aggie/Homeguard story...not so much. With is as it should be since that b-story was only really there for padding and IIRC has very little of consequence going on.
The music is very hit and miss IMO. It's very moody ant atmospheric in the scenes that call for it, but the second anything action related happens it feels very awkward and just falls totally flat.
I LOVE the "running" drums in action sequences
It's like Phil Collins' In The Air Tinght
playing during a Car chase
I think what bothered me was the tempo not matching the visuals. Admittedly it's better in the show than in 'A Call to Arms', but to me it never came close to what Christopher Franke did in B5, even early on.
I guess it was too great a cognitive dissonance for my poor little brain. Like playing thrash metal during a performance of swan lake.