Pros: it's stable, supports several different transfer methods, is completely simple (and still flexible) to admin, and it's totally reliable. It does file deduplication and compression and manages its own pool very efficiently. I've had it responsible for networks of 50+ systems before and it worked without any trouble. It has a sensible and reliable email notification system. It gets the basics really right, which for some reason seems to be a problem with a lot of other backup software. The documentation is good. The developer is friendly, has been working on it for over a decade now, and is easy to reach by email. There's a quiet mailing list with some folks that have used BackupPC for Truly Large Networks and know it about as well as the developer. Version 4.0 is pretty awesome. It has saved my butt a few times and a client's butt at least twice. Also, it's free, assuming you have a server somewhere to run it on; it's not a SaaS or PaaS or YaWaaS, so there's no monthly cost.
Cons: it doesn't do encrypted backups. It's written in Perl, so that's probably a deal breaker for some people who don't know any better. Initial setup can be a bit of a pain, especially if you're new to it. The web interface doesn't use jQuery or LESS or CSS3 transitions or a lot of stock photography, so some people might find it scary-looking. It doesn't hold your hand, you'll have to be comfortable with the CLI every once in a while if you need to do something fancy (like, say, restore a batch of files to their original locations using a text file as input -- which I've done with it, btw). It won't make you coffee in the morning.