From the reviews I've read, it's silent, but if you're looking for performance watercooling, then you'd best check elsewhere. If you're happy with a midrange heatsink's temp performance but don't want noise, that'd be great. However, if you're planning on overclocking and/or really tweaking that machine, it simply won't be an effective cooling solution. The last con is probably pretty obvious, but the size of that thing isn't going to make it something too easy to move.
Personally, if it were me, I'd look at a Koolance EXOS instead. The performance is good and you can select the fan speeds to give you quiet or high performance...it's also a bit easier to work with if you move your case around. The Reserator is rather pricey, and you can get better air cooling for $50 or so vs the $200 or so that thing runs going by the price I remember.