My story has a character that's a werewolf by night. Should he be able to talk or not?

No, absolutely not.

Yes, It will make the story more interesting!

If you wanna go with traditional, then definitely no. But if you wanna break from tradition, make him a new kind of character and suck the readers in more... yes, certainly you should make him talk.

totally! it would be cool to know how the wolf is feeling

No, even fantasy books have to have some element of reality and animals don't have the vocal chords or correct shape of mouth (or muzzle, in this case) to form human speech.