Help me with an adjective ...

You could just say the book illuminates the subject. Or sheds or casts light on it.
Nice and simple - George Orwell would approve.
Or perhaps a omething about the book making the subject more accessible to less academic readers?

If you want to say that it shines a light on an important subject, I don't really think you can use luminous. That is more that the beautiful glow is shining OUT of the words of the prose, not INTO the subject from the author's thoughts/explanation.
Maybe illuminating? Enlightening? Revealing? Clarifying? Making more understandable or comprehensible or giving an insight into the subject?

Now I'm liking "luminiferous" (producing or transmitting light).

I want to say that the book shines a light on an important subject. But that sounds so trite. Now what does "trite" mean again? ...

gk what do you actually want to say about the book?

Perhaps you can read it in the dark.

Have you read the book or are you just reading reviews? Is the reviewer someone you like?

Please read the book and let us know whether you would describe it as luminous.

Is it radioactive? Some radioactive elements glow in the dark.

It sheds some light on the subject, probably too much? Glows in the dark, so you can read it with the light out?

Seriously, I'd have thought the prose in it might be described as luminous, if it drew pictures in the mind that seemed to glow with an inner intensity (Dylan Thomas?) but I am not sure a whole book itself would be luminous. If it were, it would be a bit overpowering, you might be overcome in the luminosity.

I said that before I Googled. Then I did find it as a definition.

I am seriously missing some luminousity in my life.

nina I quite light enlightening ...

I am currently "crowd sourcing" I believe (by doing this).

I had to look up "coruscating" but I see it means "striking in style" so I may go with that...

Do keep them coming, please!

According to one definition I have just read it means that it is "coruscating". So now it is perfectly clear isn't it .

I'm the reviewer and I'm running out of adjectives

Or perhaps characters, scenery etc. are well described.

I agree, a bit pretentious.

Enlightening ?

Wear dark glasses

That the reviewer was a pretentious prat