It's obvious that we nerds love Tolkien, but hopefully none among us think he was perfect. What would you say is your least favorite aspect about his mythology? It can be perceived plot holes, bad dialog, poor character development, whatever.
For me, it's probably how fathers give their sons similar names (Finrod, Finarfin, Fingolfin, etc). That gave me untold amount of headaches when I was first delving into The Silmarillion. I don't have much bad to say about anything else. Now, if Tolkien didn't also agree that the Valar were totally stupid* giving the race of Men the shaft, that would be my choice. It just pissed me off how the Valar coddeled the Elves and totally threw Men to the wolves, metaphorically and literally. It's like they didn't care.
* - Specific quote:
Everybody, including divine spirits under god, makes mistakes in this mythology, and of course the gods made a primary error. Instead of leaving elves and men to find out their way under the guidance of god, they invited the elves because the rebel amongst them, the wicked god Melkor, was alive and devastated a large part of the world.
They took them back into their paradise in the west to protect them, and so the whole machinery starts from the rebellion of the elves, and therefore, in rebellion of the evil they did in their bursting out from paradise.