In a nutshell, the disadvantages are concentrated primarily in and around tempdb. You need to be sure that you've configured that well so that it performs handily. Other than that, the advantages are pretty huge. You'll see radically less blocking within your system because of the ability to read data at the same time as it's being written, but you'll avoid the insanity of coding NOLOCK into all your queries. Just get tempdb configured right first.