I also have issues with the fit, the side of the top and bottom, at front and back, do not align properly. You make one side's top and bottom line up, say front R then the back L is thrown off. Fortunately the mis-alignment is not enough to cause problems putting the back and front covers on, they do not show significant gaps and stay relatively flush. Sliding the shelf in was more difficult than need be, maybe spraying some silicone on the plastic wrapped edges would help? It didn't require my full body weight as another's review.
The screws seem on the small side, and look fragile as though they could strip even being a hex and not slotted or phillips. Definitely be careful and don't over tighten the back plate or your iMac may be permanently locked into the HiRise.
These two issues have me knock it down one star each. It definitely tidies up my desktop as I can place a TB HDD across the top and not have to reach around either side to turn it on. I placed a USB hub inside the HiRise out of site, and another TB HDD on the 12 South BackPack behind my iMac.
Overall a great idea but for $80 QA should be better!
I read a number of reviews all praising the novelty of the HiRise and the ease of installation. I decided I wanted one since it's a much more elegant solution than raising my iMac with a textbook.
I expected the installation to be a breeze, but it truly wasn't. It looks very foolproof, with clear instructions on how to assemble the HiRise. However, for some reason, the one I received was just not precisely cut to slide together easily. I eventually needed to use nearly my entire body weight to slide the top and bottom pieces together against the floor, which from other reviews I read was absolutely not necessary. I can only chalk it up to back luck and the top and bottom pieces were just not made well for each other. It's safe to say that I will probably never disassemble the HiRise ever again, if it's even possible.
Now that I've set it up though, my desk looks amazing! Too bad the installation had to be so rough. My suggestion to Twelve South is to improve on the QA and perhaps test the fit of the top and bottom pieces before packaging.