extremely well corrected lens
a very sharp lens, which has no CA's at all from f 6,7 to f 11, even in extreme situations.
very sharp,when stopping down to f2.8. extremely sharp from f4 to f8.
love it very much because of its high contrast, nice colors and wonderfull bokeh.
macro shootings with macro ring or converter use no problem
very highly recommanded:-) a really professional lens (similar lens of Zeiss is much more expensive)
Depends which Zeiss you're comparing with I would guess. I really like the 50 f/1.8 also and do think it "hits above its weight class".