I like Mabel, there is one in DS1's school. I love Maggie. Before DS1 was born DH's dad had been doing their family tree and the name Maggie Bella appeared on it several times, short for Margaret Isabella. We were so tempted by it, family were horrified, alas no girls yet and now we have a Magnus, so we can't really have a Maggie as well (currently pregnant with no. 3).
I think it's just ok. A friend's mother used to apply the rule that if it sounds like a "maid's name" it was no good. Thought this was very snooty...but can sort of see her point - Mabel and Margaret (a name I loathe) both sound like they should be bellowed by the housekeeper in a costume drama.