Oh, it depends. As I said I really like girls with a swiss accent (ever since the Euro 08 haha) but on the other hand there is this crazy stalker bitch with a very strong regional thuringian accent that wouldn't leave me alone. In her case, I always wanted to rip her tongue out...
So generally speaking, it might add a lot of charisma because accents are deeply rooted into ones personality. They're true, not staged and hard to overcome (especially if these people just let loose). But they also might be annoying as fuck and I simply can't take someone seriously if he or she has a very broad accent (especially saxonian haha).
However, as I'm working as a radio moderator, I'm glad for having just a slight accent (and having that one pretty much under control).