To be clear its not just hiding your IP you are proxying all your potentially sensitive data via their servers. Also bandwidth may be cheap but its not free. It mentions a paid option for a bout 5 euros a month that is 10x faster with unlimited bandwidth.
I interpret this to mean that the free option has a finite supply of bandwidth and is slow which is logical because otherwise people that want to watch 4k netflix over it would put them out of business.
I also see that they offer a browser plugin but don't seem to provide say an openvpn connection which seems inferior as that protects all forms of data rather than just browsing data.