Hi jonsd,
On “average” … it would probably be a little on the firm side for most side sleepers but each person is unique and can be very different from someone else so it may work well for some side sleepers but not work well at all for others. Regardless of how it works for anyone else though … the only way to know whether it’s a good match for you would be based on your own personal sleeping experience. I would never make a mattress choice based on other people’s experiences that may be very different from your own (see post #4 here).
If it does turn out to be too firm for you then you could either return it and start over again (and there are many other good quality/value options that would be softer) or you can add a good quality but softer topper if you need some additional softness or pressure relief.
Phoenix