I have never seen a wind turbine in person before, so my opinion may not be the best source for a debate, but from what I have noticed from various pictures and videos from researching the topic of wind turbines is that yes, they can be annoying but not in an visual way. In my opinion, they are quite natural when put in the right landscape, like a large open plain. At least what I am trying to say is, they don't look half bad as long as in they are in the right area. They same goes for many other things too if you think about it.
Many people find wind turbines required for wind power to be quite ugly. However, these turbines can be used in an aesthetically pleasing manner. They need to be spaced out and away from heavily populated areas, though. Plus, they need to be put into landscape areas where they make sense rather than look like eyesores.
This answer is only addressing what is asked, which is the aesthetics. Wind energy requires a lot of equipment for a relatively minor output, and it's not a pretty addition to the landscape. That said, it's to the best of my knowledge a harmless one, and it is a renewable energy source that I'm in support of.