I used to play one of the Franck chorales on the organ (#2). It's a great piece, full of dark Romantic lushness. Some music critics felt it was comparable to Bach's organ music.
The violin sonata should be checked out as well.

I enjoy some of Franck's organ music, not so much his orchestral work. I found his D-minor symphony to be rather dull.
In any case, I used to play the game of "composer X who I admire was influenced by or praised composer Y, therefore I need to have a higher opinion of composer Y," but now I don't see the point in doing so.
No matter how much praise Debussy, Ravel, and Shostakovich lavish on Mussorgsky, I still can't see the alleged "greatness" in most of Mussorgsky's compositions. Similarly, Wagner considered Carl Maria von Weber to be the greatest influence on his musical development apart from Beethoven, and while I find Weber's operatic overtures pleasant enough, I have yet to be convinced that Weber deserves to be mentioned in the same breath as Beethoven.
On the other hand, Brahms' praise did lead me to give Dvorak's cello concerto another hearing, and I've grown to appreciate it. It's a far greater work than Dvorak's overplayed Symphonies 8-9.

César Franck had many more titles to distinction than having "inspired" Debussy!!
He founded a whole school of composition and wrote quite a few highly distinguished pieces.
Scostatevi profani! Melpomene son io

That was beautiful, thanks.
You're my wife now.