I’ve used it for the last year and haven’t had any problems with it. I do have to add coolant to it every couple months but it’s not really that big a deal. I use the system built into the Thermaltake Armor LCS case which is equivalent to a Thermaltake Prowater.
If you take your time and do it right you should never have a leak. Quality parts make all the difference as the cheaper ones tend to corrode and leak.
As to heat, it helps some but not much. The same heat is generated no matter what cooling solution you use, the advantage of liquid cooling is that you can quickly channel that heat to a radiator to dissipate instead of leaving it on a heatsink attached to the CPU/video/RAM. The part you’re cooling is significantly cooler but your room, not so much. As to noise, there should be significantly less noise as radiator fans don’t have to spin anywhere near as fast as a CPU fan. I can’t even hear my two 120mm radiator fans.