Undoubtedly Assad is a harsh leader. To be a leader in that part of the world one would have to be. If Assad were removed from power whomever took his place would have to be at least as bad.
From what little I have read, it seems that maybe that's Israel & Saudi Arabia's goal - a fractured and weak Syria. It worked with Iraq, and it appears Syria is next. That may be inline with Israel & Saudi Arabia's goal, but it empowers the Al-Quaeda/ISIS/etc groups. And we all know how those radical organizations feel about the west and America in particular.
It seems that by trying to remove Assad from power we're going against our best interests.