1. The UI is horrible and not amenable to sufficient customization. Xfce, bspwm, and i3 are all substantially better from a user experience and getting-things-done standpoint.
2. The availability of tooling for basically everything other than graphics design or video editing is significantly worse than for Linux.
The availability of tooling is just fine. You may need to compile from source, but that shouldn't be a big deal. Otherwise there's also MacPorts, Homebrew, and fink for pre-built packages.
