I will always rate a well-crafted solo way above one that's just a flurry of notes. But I can also LOVE a fast solo, that incorporates unique musical ideas- diminished runs, harmonic minor, voice leading, etc.- because even though it may be getting into shred territory, I can still hear that there's much more to what's going on than just playing at a blistering speed.
But I also "get" that there's a time and a place for anything the player has to offer a solo. If that solo needs an ending that a blazing, ascending run up to a high D bent 1 full step to an E, played at 800 notes per minute, to sort of punctuate the whole thing, then hell yeah! In those kinds of solos, I feel it fits, musically, and yes, it's also impressive.
I find nothing wrong with being impressed by a guy who can do that, just as I'm impressed with how some people can write a piece of music that takes me on a journey, and raises the hair on my arms, and sounds absolutely spectacular through a killer system, because that person had also learned how to record it well.
But I will also add, that in my own tastes, and my mind's ear, there are players for whom shredding is all they seem to bring to the table, and they get boring real quick. I can hear that 'neo-classical' element that Yngwie has, but after 3 songs of being blown TF away, I'm done.
Like many things in life, it's about balance. I have mad respect for the shredders, as long as they have enough of all the other things that make a solo interesting.