This is a review for a doubled-layer open frame rig. The design is similar to this one.
The unit comes like an ikea package, in a flat parcel. So if you like assembling ikea products and playing with erector sets, you will have fun. No, I wasn’t around back in 1913 when erector sets started. The assembly is easy enough, and they include all the parts and screws. Even some spacers for the motherboard
The parts are well done, with no sharp edges. The powder paint is applied evenly and didn’t seem to have missing areas. Overall it is well designed and thought out. The instructions are good, though some steps are a bit vague. The hole threads hold, even after some minor abuse 
The design is flexible and you can do place the gpu towards either side. There are enough holes to let you build the frame as you like. The unit seems stackable, but guess you need some extra hardware
The bottom plate allows you to mount the motherboard, 2 psu, a hard drive. Mine came with a power button to boot but would have been nice if they included a mounting plate for the buttons and system leds.
As to the issues:
There aren’t enough holes to mount the psu firmly. I was only able to use two holes on the psu, and both on the same side of the unit. So it can swing a little if you move it (like when plugging the cable) or the frame. There is an included plate but was too short to reach another hole. Maybe if you mount the psu differently, but wanted the fan to the outside of the frame
Didn’t try it, but think it needs some holes on the bottom plate to mount a server psu onto it. Like you can with the hard drive.
Even though there is plenty of space between the cards, you might find it hard to work if fully populated. Had to remove the top cards to work on the bottom ones.
If you use the molex connector on the risers, the edge most card will push those cables against the crossbeam. You might want to connect the riser before installing. Though there is plenty of space between the cards, it is hard to work.
The biggest issue is the placement of the fans, which leads to running warmer or needing external fans. The design places them opposite of what the cards like to do (exhaust hot air on the rear fan). The fans are closer to the rear (opposite side of the mounting bracket and monitor connectors). It is ok for long cards for the fans to exhaust the hot air from the rig, but too far for short cards.
If you push air towards the cards, you will be moving it towards the forward side of the cards. You can attach fans on the other side if you jerry-rig them.