Jeffery's main accomplishment during his tenure at LucasArts was forging new relations with external developers, such as Planet Moon Studios, The Collective, Raven Software and BioWare.
However, he failed to achieve his goal of turning around a creative slump at the company. According to Jeffery LucasArts had too heavily relied on its Star Wars license, but successful new IP failed to materialize. Games such as Gladius and RTX Red Rock did not achieve critical acclaim or great sales; follow-ups to classic LucasArts adventure games, Full Throttle: Hell on Wheels and Sam & Max Freelance Police were cancelled, to much dismay of the fans. (An online petition to save Freelance Police got over 31000 signatures.)
Simon Jeffery later became the subject of several fan animations in the LucasArts fan community, often depicted as a Jesus-like figure.
Jeffery is a big Star Wars fan and once claimed to have seen Star Wars Episode IV: A New Hope 93 times.
Prior to joining LucasArts Jeffery worked in a number of marketing, business and development roles for Virgin Interactive and Electronic Arts.
At Sega, Jeffery plans to recruit Western development houses to work with Japanese Sega IP and strengthening Sega's game production in the West in general. 
In August 2007, Jeffrey was interviewed by BusinessWeek magazine, which had the following lines:
Jeffery is looking beyond Sonic, which he says is "an amazing recruitment vehicle" for younger gamers but "loses its cool factor when you get about 12 years old."
|SEGA of America CEOs and Presidents|
|1980s||David Rosen (1975-1986) | Bruce Lowry (1986-1988) | Michael Katz (1989-1991)|
|1990s||Tom Kalinske (1991-1996) | Bernie Stolar (1996-1999)|
|2000s||Peter Moore (1999-2003) | Simon Jeffery (2003-2009) | Mike Hayes (2009-current)|