Indeed, there are people on ZBrushCentral (boozy_floozie for example) who make illustrative art entirely in ZBrush (with maybe a small amount of PS touch-ups here and there), try doing that stuff in Mudbox ;)
Maybe I'm crazy (and lucky to have never had major issues), but I love that Zbrush is unique and "quirky". Sure the interface has a learning curve, but I'd say it's more about just understanding how it works on a basic level and getting around what you're used to as opposed to what it is. Once you get your head around it…