Don't just drop the slider for the sake of it. Although radio buttons are more common, one big benefit to the slider is a simpler, less-cluttered UI. Does a user really need to see a long list of the same options for every question? Why not keep the slider, but fix it's shortcomings. Make it beautiful, not boring.
So what are the downsides of a slider, and how can they be addressed:
Can't easily see all possible values
A user shouldn't need to scroll the whole slider just to see what options can be selected. You already display the "selected value" of the left. Why not list all the values on the left, but make the non-active ones a lot less noticeable (e.g. semi-transparent), maybe even a tick icon on the selected value.
You don't want a slider that changes position for every pixel. Use a slider that supports fixed increments, and keep the number of values to a minimum. 5 values, or 7 at a push (less values = less prone to miss-selection). Play around with the height of the slider until you get something that feels natural - ask some potential users to try it out if possible.
If using the suggestion of listing all items, why not also make them clickable. Click an option, slider adjusts to match. Easy to use, and looks good too. Best of both worlds.