Portaball experience or opinions?

I'm considering the purchase of a 10 or 12.5 inch portaball. I like the
simplicity and portability of the design, and the apparent quality of
the engineering.

I've read some reviews that say image quality is great, but there may be
some problems with balance and with movement because there are no fixed
axes.

Does anyone else have a view from personal experience of this type of scope?

Thanks

john