I've been using AIDE for a number of years to keep tabs on my home server.
1) The ups of AIDE are that is is easy to use and very configurable. The downside of AIDE is that it only does file integrity monitoring. That isn't necessarily a bad thing, but some of its competitors offer more tools.
2) I've found it drop-dead easy to use. You'll spend a bit of time figuring out the config file to start, and then a bit more time figuring out what directories you need to monitor in order to keep your signal/noise sane, but overall it is pretty easy.
3) See Tripwire
(open source version), Samhain
, and Osiris
. Whether or not they are "better" really depends upon your requirements.