They do have a certain awkward charm to me. Except abominations like Golbat(which tbh looks pretty funny at least)
I love Clefairy's sprite tough. No idea why, maybe it's the lack of that ugly tone of pink it usually has.
The worst out of the bunch was Mankey back then. I really liked it because of the anime and in Yellow(which my brother got before I got Red) it looked really good. Then I saw it first time in Red and well... it was baffling. I still don't know why they couldn't put more effort in some sprites yet they could in Yellow.