The last time I tried MonoDevelop (let alone on a Mac) it was a total disaster. I hope it's better now. I am pretty comfortable with Xcode, but "native" Mac apps in C# is a pretty good reason to consider switching to something else.
I open the new file dialog. Type in a name, try to copy the name... and it closes the new file dialog! Apparently Cmd-C is bound to cancel. Okay, so it's a little quirky. Let's try again.
I create a new file. Type some text. Select Edit->Copy this time and... it's crashed.
Maybe I'm unlucky.
I install MonoMac, restart, create a project, write some code to display an NSAlert, press build and
Build failed. ~/.config/MonoDevelop/addins/MonoDevelop.MonoMac.2.4.0.5/mono-version-check does not exist.
Jesus
EDIT: As a bonus, a process called mono has been running at 100% CPU for the last half an hour.
EDIT 2: After using it for a bit longer, the editor itself is actually not bad. It has all the features you'd expect and autocomplete seems well implemented. But this software is just far too buggy for any kind of serious day-to-day use.
MonoDevelop on the Mac needs a lot of polish. Structurally it is pretty good and it does get the job done. But there are enough UI and focus related quirks to make me want to pull my hair out.
I say this as a big fan of the Mono project, but if you are remotely picky about native OS X look and feel, brace yourself before opening even the latest MonoDevelop IDE. In that regard, it is grim.
My experience with MonoDevelop 2.4 (the latest release, I believe) on OS X has been pretty good. I use VS daily and dabble in XCode, and MonoDevelop is definitely more VS-like than XCode-like, so it may be a bit unfamiliar for you. Certainly there's room for improvement, but it's relatively solid in my opinion.
