Part of me thinks that PowerShell has seen less adoption in the Unix world because of the prevalence of camel case. The few times I used PowerShell, the discoverability of what I could do was low and the verbosity of examples was high. It took me too long to do my most common tasks.
I've seen several people who like PS say its discoverability is actually pretty great compared to Unix shells - for instance, the convention for cmdlet names is always "verb-noun" ("action-object") and (maybe, don't quote me on this) the set of blessed verbs people are supposed to use in cmdlet names is fairly small. So, when you want to do something, you try the verbs that seem closest to what you want to do and the names of the (usually application specific) objects you're working with and that gets you quite a long way down the road.
Also I think PS commands aren't case sensitive, though for readability one would probably want to keep the camelcase anyway.
