Luuup seemed like a great idea in theory, but in execution, it fails pretty hard. If cats only pooped it would work mostly like a charm (though some sand will still make it past those supposedly sealed interlocked sifting trays, so keep a mat under it) but the Luuup's downfall is that cats pee too.
Clumped litter sticks to the walls of the Luuup, regardless of how long you've waited for them to dry out. Also, litter ends up clumping IN the sifting slots, rendering the slot useless and requiring removal. The end result is that after sifting (and using your scooper to free those caked on clumps) you will have to wipe the whole tray clean before placing on the bottom layer. The whole point of the Luuup is to decrease cleaning time, but having to wipe down a litter tray every single time is a significant increase in the spent cleaning.
Also, sometimes as you lift the top tray out, the middle tray will partially lift out too (suction, friction, I'm not sure why exactly) and that leads to a disaster of litter dumping out the bottom try onto your floor now that the "seal" has been broken.
A better and cheaper solution can be had at most pet stores. I have a sifting litter system now that is far superior. It's three trays again, but now only the middle tray is a sifting tray, and it remains sandwiched between two regular trays without sifting slots. When you're ready to sift, you lift the top tray out and dump it into the center sifting tray. You then sift out the clumps and dump them. Then you put the sifting tray into the empty top tray, then place the bottom tray filled with the reclaimed litter on top. This prevents litters from becoming cemented in the slots because the litter is already clumped before it ever reaches the sifting tray.
Bottom Line: No, I would not recommend this to a friend