Got used to IntelliJ IDEA for about a year ago. It's nice, but my actual work productivity hasn't increased. Seriously, I now use an IDE because I feel more comfortable within IDEA, as when you're using a text editor, you don't just use a text editor, but rather the entire Unix toolchain and I got tired of stressing out my memory. And btw, I still open Emacs a lot because I'm missing Emacs' macros and undo capabilities amongst others.
If you want an IDE, sure, use an IDE. Learning a new language with an unfamiliar IDE on the other hand is a really bad idea, since instead of learning the actual language, you end up dealing with the toolset.
Features like "find references", "go to implementation", "find implementations", "show parameter list" are useful for understanding and navigating large code bases. They have nothing to do with how you write "shitty software" they have to do with how you navigate and understand the code base structure.
Writing shitty software has nothing to do with autocomplete.
MonoDevelop was forked from SharpDevelop but they diverged. Unity has MonoDevelop with Unity-specific patches and they are a little behind. Xamarin Studio is also MonoDevelop with proprietary stuff.
Speaking of the "linux version", linux distributions are very far behind in the package versions provided and the folks at Xamarin are only doing packages for OpenSuse. If you want to do development with Mono, Linux is unfortunately not a good OS to be on. Mind you, this is nobody's fault - it's just lack of interest.