Clean your iPhone contacts in a few taps

Just used this app to clean up my contacts and managed to remove over 100 entries of rubbish. It automatically detects duplicates and contacts without a phone or email etc, really clean interface.
I have soooo many duplicate contacts in my phone. It's absurd. I'm nervous this might merge the wrong ones or delete information though.
@rrhoover - I was pretty skeptical too - but this app makes a backup for you before it does anything, which is a really nice touch.