They'll never be confused with a hard-side enclosed but if you already have a high quality open trailer it is a cheaper option. I had one put on my 18' Ridgeline last year (yeah, I know, weird length but I just needed a big 3-place). It definitely does the job and I've been pretty happy with it so far.
As others have said, the cap is light and has surprisingly little drag. I had the manufacturer install mine and had it welded on rather than bolted, as I don't have any intention of ever taking it off. They threw in the fuel doors as a perk and I had the LED interior lights installed, which are really nice to have. If you live reasonably close to Montrose (I think that's where they are located) you can drive out and they will install it while you wait if you let them know you are coming and what size you need. It seems like it takes about two hours.
The thing I thought would be problematic is the rear door zippers but I've had zero problems. The nose door is a little unwieldy for one person to open and close but for a couple of people it's a non-issue.
As this photo shows, it fits just fine with my salt shields/ramps.