You want some advice? Choose well the time of year you want to go there. Depending on the time of year there will be more or less people. I chose the 2nd week of July and it was a perfect choice.
For me, it is an absolute must visit. To go by car until Covadonga, to park and to find this extremely beautiful temple in the middle of a natural park is priceless. You have to see it for yourself. The pictures and videos can only give you an idea.
We continued the visit going up to the lakes; I recommend that you do the same. Depending on the time of year you can do it by bus or car.