Does this gym truly only charge $10 per month? Or are there added fees to consider. Such as annual membership fee, sudden increases, limited use of gym classes unless you pay extra (other than personal trainers, etc.), etc. ...thinking of joining.

Yes they do charge an annual fee but you have full use of the gym at no additional charge no sudden increases

I had to pay a signing fee at something like $150. They have specials where they decrease/remove it, so if there is a signing fee you can just wait After that though, it's a pretty good deal. 10 a month + 40 a year, all classes included

Its 10 a month and 40 in march for annual membership. Thats all.