This is all about the selling you a "Device" and prices vary greatly between resellers. The devices work well, but the pure cloud solutions need a lot of work.
FreeNAS is well suited for most storage serving scenarios, whether it be for an office file server, backup destinations, data replication across the internet, or as backend storage for virtual machines. It can serve various types of clients via a plethora of standard protocols and can easily integrate with existing infrastructure using LDAP authentication and so on. It's pretty simple to use (it helps to have at least a basic understanding of the underlying technologies) and almost maintenance-free. One scenario that springs to mind that it may not be appropriate for (yet) is as S3 storage. However, S3 functionality was added in a recent release and may have improved greatly since then. I'm sure it will eventually work very well for this.
SQL Backups just don't work reliably. For us, we lost all of our SQL data backed up through the CTERA Application process. Although the logs indicated a success, that was really not the case. This came close to putting us out of business. Luckily I had taken a genuine SQL backup to a folder. Unfortunately it was a month old. We had to pick-up the pieces from there.
Don't use it for file sync and share. There are better products out there i.e. anchorworks.com
Support sucks. Good luck with response time and answers that are inconsistent between team members. For example I had to rebuild a VM from scratch. When I re-installed the CTERA client It obviously thought I was adding another device. When I inquired to tech support, one member said "copy the old Data folder" (I still had the old VHD. That did not work). The other directed me to the correct spot to just change the associated folder. The turn-around time was over 24 hours for this simple fix.
Documentation, plenty of fodder but no real tech there.
Unfortunately CTERA does not stack up well if you want a pure cloud BDR. I have use iDrive and Asigra. iDrive has similar support and SQL backup issues. Asigra can vary widely in support and price, but the software is solid.
FreeNAS effectively uses all resources really well and it is highly recommended for in premises NAS. It has unlimited ROI as it is really free and open-source. The only payment we need to pay is when we need any support from those guys. FreeNAS helps us to effectively do our work with the legacy systems as it manages all the components really well. FreeNAS although rebranded to TrueNAS will still be there until our legacy systems run.