I've used this program to do my backups for a while now. I see that others have problems over networks, but using this for local backups to a variety of disks has been basically trouble-free and very satisfactory. I had 3.3.6 and then moved to version 4, and it's not been a painful transition in any way.
I like some of the configuration options, such as automatic backups on drive mount, and the ability to set up automatic unmounting of drives once backups are completed. Granted it's mildly complicated when setting up options the first time, but the user guide and info made it reasonably straightforward, and questions I had about certain file types were answered rapidly by tech support. I use this in combination with Knox to manage encrypted disk images. Thus, I have an encrypted image on my backup disk, when this mounts ChronoSync runs a backup, and it all seems to work. It's nice running to an encrypted disk, as I feel that my data is more secure, given how easy it is for someone to steal a removable hard drive. (This is the main reason I use this rather than Time Machine). I like the control over versioning, and across a USB it's very fast.
I used to run my backups to a NAS drive, but this was always annoyingly slow, though not ChronoSync's fault as far as I could tell.
I can't comment on the network performance issues that some people have experienced, but for local backups this has been a reliable and trustworthy program, and I'm pleased with it's performance and customizability, as well as being able to find ways to configure encrypted backups. The tech support has been pretty good as well. I've tried a few different backup programs, and this is definitely my favourite.