pretty typical direct to stud acrylic unit .
we've installed dozens *.
Nothing great, nothing bad if/when installed right
They say you don't need a mortar bed under the tub, but it's best to do so regardless.
Makes it easy to get perfect level, as well as 300 pounders and/or two folks in the shower getting slippery
*Don't know anything about the one with adjustable shelve corner kit.
Never put one up, they've all been the molded in type like the shower surround in first pic
and you do know, unless you have grande wide doors, or a small shower unit, you can't use a one pc surround
(those are for new construction before all the walls are up)
..L.T.A.