I really like it a lot. I had a Revolver X4 on my '19, a BakFlip (i.e. hard tri-fold) on my '09, and before that I had Retrax covers on a couple of trucks.
I like the X4s best of them all. It's almost identical to the X4, which I also really liked. But, after 3 years, the felt runners on the underside of the X4 were falling down. The heat got to the glue that holds them on. The X4s has some kind of rubber things instead of that felt, so I don't think I'll have that problem.
I like the X4/X4s the best because it takes up no room in the bed when it's rolled up, like the Retrax did. It doesn't block my view out the rear window, like the trifold did (when both are rolled/folded up). I think it looks better than the trifold. And I don't need a separate key for it, like I did for the Retrax. If it's closed and I lock the truck, the cover is secure.
Oh, and I had the factory soft trifold on my '21 for the first month or so. That thing sucked in comparison to any of them. After being used to the X4 on my '19 and going to the factory trifold, the fact that I had to open the tailgate to close the cover was really aggravating. Also, not being able to put the trifold on (closed) when the bed was totally full really sucked, too. You have to have a little room at each corner for the locking levers to swing through with the factory trifold. Also very annoying. And, with the factory cover, when you have it totally open it is not attached to the truck at all, so you can't drive with it on the truck but totally open (like you can with any of the others). All of that plus the fact that any truck with the factory trifold has different rails, which you have to replace before you can install almost any other cover, just makes the factory trifold a super, major POS. (but I have one with the rails in my garage, if anyone wants it LOL!)
Also, I think I'm a Bak customer for life now. I emailed them about the felt falling down on my X4 and also it had developed some cracks in the vinyl on top. They said I was just a month or so outside of warranty but they were going to send me a brand new whole top at no charge. That is pretty awesome, I think. As it worked out, I traded my '19 for my '21 before I got anything worked out with Bak, so I ended up telling them no need to send me a new top, but I did want to buy a new one for my new truck. For that, they gave me a 50% off coupon for the new top.
Bak went really above and beyond on customer service, which just makes me like my X4s even more.