Hi Peter,
I would be happy with that image, I know its not exactly round but there is some detail and also a moon shadow by the look of it.
The wobbly shape is probably the seeing, like Mike said, I have also noticed Jupiter is like its sitting at the bottom of a shallow creek of muddy water this week.
Rule #1 of planetary imaging: Listen to Mike Salway.
Rule #2: Read everything by Mike
Rule #3: If all else fails see rule #1 & #2.
Cheers
Chris