But there is a downside to the new shaders, if you have a great graphics card, like i do, you'll be fine, if you have some intel graphics, then you cant run the new shadows and shaders, I have a nvidia geforce gtx 660.
That's not really a downside.
A downside would be, for example, when you have to remove one feature in order for another feature to work properly.
Removing terrains and interiors was the downside for adding shaders.
Not being able to run shaders would be a "problem" with your graphics card, not a "downside" to shaders.