Loud fan. Low flexibility hoses. Gurgling/rattling/clicking pump. Assembly nightmare. Cheap Screw holes mounts. Screw holes are easily stripped.
All in all, cheap product made out of cheap parts.
I've got the Seidon 120M. It was on sale for $5 less than the 120V, and came with the screws to mount a second fan for a push/pull configuration. I already had 4 spare 120mm fans on hand, so that's what I did.
Fan is easily regulated with a fan controller or in BIOS. Easy fix, so quiet I can't hear it. Hoses are meant to be low flexibility. They are made of high strength material so that they don't spring a leak! I have not had any issues of this gurgling/rattling/clicking pump, though I've heard a few people say that. More often, I hear people say how quiet it is. I believe the people who have those issues may have gotten something that had already been mishandled/dropped beyond the capability of the product to absorb it. Cooler Master has been good to me in the past when an item needed an RMA.
I have also heard people say the screw hole mounts are cheap. They are not. However, you need to understand that the screw hole mounts are made of aluminum, and are as sturdy as aluminum can be, which aluminum will give. Those mounts are made to be "finger" tightened only. You should never tighten them as you would the lug nuts on your car. Once they hit friction, stop. With the other screws, like mounting to the MB, I tightened them as tight as they would go and then gave them another quarter turn by hand. All in all, it was a good experience mounting this. However, I probably have more experience working on electronics than most, since I started doing repairing, building, and assembly of electronics as early as 1974.
Assembly of a liquid cooling system is not for the feint of heart. If, however, you have limited space either because of your case dimensions, or position of your memory next to the CPU and you have memory with large fins like I do, then a liquid AIO system may be the way to go.
If you decide on a heat sink/fan combination (air cooler), then make sure it won't interfere with your installed memory. Measure everything multiple times, and get correct dimensions on the product you want to purchase to make sure you won't have a problem with it interfering space wise in your case.