I am not a 5D3 user but I recently went to my niece's wedding in Dublin and was VERY impressed at the photographers images. I managed to have quite a long chat with her between shots as I was interested in her gear and technique. She shot the whole day, and night, with a 5D3 + 24-105 F4 and a 580EX2. When flash was inappropriate she just used the 5D3's very good high ISO. She was shooting from 14:00 to 22:30 so there was quite a wide range of lighting conditions but the 5D3 didn't fail her.
From what I have seen and read the 5D3 is probably the best "All round" camera going at the moment at anywhere near a sensible price.
You WILL be happy.
Life is for living, cameras are to capture it (one day I will learn how!).