Generally speaking, nearly every product out there has had (historically) some holes, or missed detections....so I would not be surprised.
Not an expert on it, but used their enterprise tools about 10 years ago, and it was better overall (especially on the Mac side) compared to Symantec.
Based on that, I have used and liked their products off and on for years, and still like them overall. Not claiming they are the best.
The parental controls will be very valuable to some, worthless to others.
According to this review they are in the top group overall, but lag a bit in hit to system performance compared to the best. I assume the tests are with live scan, and on a Mac, I tend to turn off live scan to negate performance issues, and just run scheduled scans.
My take: Sophos is adequate protection, with adequate performance, with zero nag to upgrade to a paid or pro product. It stays out of my way, which is almost as important as security performance.....and works equally well on Macs and Win.
The review I linked to shows the top performer:
virtual tie for ESET and BitDefender. Both are paid tools though. So....not really fair to compare to free.