Definitely a 5 out of 5 for product performance, 4 out of 5 for ease of actual installation, but 2 out of 5 for handling due to composition. Although it's generally expected that insulation is unpleasant to work with, this was extremely harsh to handle as a skin and mucous membrane irritant. Especially in a sweltering, tight area. It also occasionally crumbles, releasing even more particulates into the air. Just being in the same room with the raw insulation causes me discomfort, so be sure to read the safety precautions on the packaging prior to handling, and definitely do not allow children or pets near it. Respirator masks (3M model 8210 or equiv. are recommended) are an absolute must and I personally recommend shop-vac-ing the area ASAP with an appropriate filter to avoid tracking. Once it's installed, obviously all that matters from there on is ongoing product performance.
There is no paper-backing, so there is no stapling and the batts cut like butter with an inexpensive insulation knife. I was initially anxious to get to work and tried to use a drywall saw for the first couple, but it made a huge mess. Don't do that - lol. When cut with the proper blade, the batts install impressively rigid between beams and stay nicely in place.
I got this insulation for finishing the exterior walls of my basement and to weatherize a small, awkward, exterior-backed/attic-type crawl space that has been a heating/cooling nightmare for two bedrooms. In the basement, the vents aren't completed yet and the ceilings aren't insulated, so there no way to reference a change. But as for the aforementioned crawl space, there was an almost immediate temperature difference in the adjoining bedrooms after installation, as well as a notable sound barrier between the rooms it separates. So I'm quite confident in how it will handle in the basement.
Almost everything about this insulation is pretty amazing; going greener with 70%+ recycled material, safety benefits with temperature thresholds of 2000F+, water-resistance and sound-proofing. I've also read that the lifetime energy savings produced via the mineral wool will exceed any difference in manufacturing energy of the fiberglass currently used. Just cover yourself well during installation, then kick back and enjoy the lifetime of energy benefits.