Have to agree with Diogo (and in public as well, darn it
) - Spinball is nothing like a wild mouse. It feels a ride with intense sweeps, but as he also alluded to, an unbalanced car is brilliant/awful dependent on how you experience the rides.
There is Heave-Ho - it is a gentle, kids, spinning pirate ship - I hated every second of it, yet I still used to ride Spinball all the time. It leaves you feeling a bit dizzy, but not disorientated - however last time I rode was on an unbalanced car, in the wet and cold at night, and it was viciously fast, intense and painful. Still not as bad as Chessingtons version though, which was just way too rough and spinny for me. Certainly, they don't ride the same if you go on one and use it to compare to the other.
I would never ride it again on the three person wet day. 4 however, and it is definitely more coaster than spin - and is pretty well liked on these forums, and packs more coaster intensity and force than you may imagine. It looks tame, it really isn't, but not in a "spinny" way which did surprise me.
As for busy days, from sort of May onwards, you can end up with Schools - I have tried to find quiet days lately and failed. Sometimes they prepare for busy days, and it is quieter, which results in an unprepared quiet day, when they get unexpectedly busy. They are worse in my opinion. With The Smiler due to open, people may hold off, but given SW6's opening year, every day I went regardless of when was absolutely rammed - and I only went "off season" week days!
It was quite unacceptable that so often they were unprepared. I hope they learn from that this year, and air on the side of "it will be busy" rather than some of the ridiculously understaffed days I went on.