Contrary to popular belief, ZZ is not a bad series....
It's more a tonal whiplash. People coming off Zeta are expecting more of the same. A dark, grittier telling of Gundam. Then you're hit with the early episodes of ZZ and it's almost the three stooges levels of goofy compared to Zeta. Compared to the original series Zeta is just inherently more depressing; and then you're snapped into a more light-hearted story (relatively speaking) and it throws you off.