It's pretty reliable and does not require any user-servicing.  This particular AIO model has been used by Dell for a number of years (MH0HN) starting with the R5. Retail wise it is comparable to a Corsair H60, if that's any help.  they both use an Asetek pump.  
Hi guys, I have an Alienware R11 on its way, and I got the AIO liquid cooling option. For those of you with any experience, how reliable and safe is it? I'm a bit paranoid about it leaking all over the other components in the computer, but I wanted to give it a try because of the better cooling.
Aurora R11, AIO liquid cooler reliability?