I play near full Light, or sorta on the Dark. I can't resist certian DS options like chopping down largo because he whines too much and wants to chisel me out of my hard pillaged credits. Or telling Nurik Sandral that his son is a Cath Hound chew toy.
If you play full Light, invest in buffering powers, and expect to be bothered by people hitting you up for credits. And the game will take longer because there will be a lot more conversations with the people that dark Siders normally tell to bug off. But you learn more of the story that way. Also, you take on more lengthy quests, often to revisit planets. As a dark Sider, there are several planets you are banned from due to your actions.
Light Side may be slightly easier due to some powerdul buffering force powers and robes, Dark Side carries certian handicaps with it too. You may be banned from returning to planets, and some Dark Side choices effect you on other planets as well.
FS