Google supports URLs as defined by RFC 3986. Characters defined by the standard as reserved must be percent encoded. Unreserved ASCII characters may be left in the non-encoded form. Additionally, characters in the non-ASCII range should be UTF-8 encoded. When possible, use readable words rather than long ID numbers in your URLs.

Shorter URLs are, generally speaking, preferable. You don't need to take this to the extreme, and if your URL is already less than 50-60 characters, don't worry about it at all. But if you have URLs pushing 100+ characters, there's probably an opportunity to rewrite them and gain value.