Simple and reasonably effective
Delivered quickly by MowDirect. Pretty easy to assemble (though the instructions included covered two different models than the one purchased) and has virtue of a simple design.
Barrel appears robust and overall pretty easy to use - drop the pin into the hole for tow-ball attachment on your tractor and secure with an R clip. Just about bang-on size wise for a tractor with 50" cutting deck and side discharge so little overhang beyond the width of the tractor, so less its pretty easy to ensure that you leave enough width when passing solid obstacles.
With the roller filled with water there's a decent enough weight to have some noticeable impact on uneven ground - but don't expect it to flatten a bumpy paddock!