I was out of the Mac game by then, so I'll leave judgement to those who've actually used it, but: as bad as Windows ME?
Mac OS X 10.0 had lots of issues (read the old Ars Technica articles on OS X) but the OS rapidly improved. They all had the solid Unix underpinnings however, and I'd rather use 10.1 than Windows ME. A lot of the issues reported were people moaning about differences from classic Mac OS too, rather than actual flaws like Windows had.
10.2 brought OpenGL accelerated desktop compositing amongst other things, 10.3 brought the very useful Expose, and 10.4 (the first version I used) was very solid.
