Is it stable and light on the system? And how is the configuration, settings stuff?
First I want to make clear that I'm using the free version and not the beta one with the extra features.
On my system it runs very smooth. I didn't notice any slowdowns during the past months. Also when downloading files, there is no lag because of scanning. I had performance issues with lot's of other antivirus products on my laptop, but never with Sophos. Also it is very stable. I tried it the first time when it was still in beta in 2016, and even then it was very stable. No issues about that so far.
Concerning configuration and settings, there is not so much room for configuration at least not for the free version. If you try the beta (which you can use for 1 year for free after the beta stage will be over), you get more settings and protection modules. The free version, which I am using, consists of signature based protection, PUP protection, a very good web blocker, parental controls, protection based on file reputation and a completely automated HIPS module for detection of suspicious behaviour. The (in the future paid) beta version adds keylogger prevention, more sophisticated ransomware protection (i.e not only signatures as in free version) etc.
For the settings, you need to login into the dashboard at Free Antivirus for Home Networks: Secure 10 PCs and Macs Free | Sophos
. Everything is managed there, there are no local settings on your machine. The settings I use for the free version are all default settings (So real time protection, web protection and PUP enabled). You can adjust the web filtering as parental control under the web filtering tab if you want, but I don't do that personally. The only setting I changed is under protection -> Web -> Download reputation, where I set the level to strict instad of recommended, to get more protection, based on file reputation.