Synthisized surround is exactly what is sounds like. A unit takes two channels and extropalates data and creates a synthizied surround matrix which is then sent to the appropriate speaker. Technology to do this has been around since the late 1980's and has improved greatly. The next question is implementation. On last years's Vizio soundbar, I felt their implementation veiled the sound. I could hear more detail when I turned the feature off which is where it stayed the majority of the time. Of course, after years of experimenting with the simulated surround of a Yamaha YSP I gave the unit to my son as I never found a mode o setting that I felt was accurate or that I liked and was not overly impressed with the units two channel reproduction.
The only way to tell how this affects you is to set up a unit and listen.