Ceylon vs MS PowerShell

It has a Web IDE: http://try.ceylon-lang.org/ with impressive demos: http://try.ceylon-lang.org/?gist=bd41b47f325b6d32514a so you can try it without installing anything, and see the JS generation / interop in action.

The compiler prevents you from using a potentially null variable, unless you check it is not null. Ie. it forces you to check a potentially null value before using it.
The type system is strict, but flexible, allowing union and intersection of types, covariant and contravariant types, reified types, etc.
Type inference and union types allows a dynamic programming style, close of JS spirit.

It brings type safety to JS, allowing to define interfaces to existing JS APIs, yet using the dynamic keyword for flexible calls in the JS ecosystem.

Ceylon has reified generics, so it doesn't loose the type of collections at runtime. This makes autocompletion, debugging, etc. first-class. The Eclipse plugin makes it a full-fledged Ceylon IDE, and an IntelliJ IDEA plugin is in the works.

Gavin King, main author of the language, has a great, clear technical writing style, making understandable difficult concepts like variance or sound type system.

The language specification is very complete and up to date; also, the language module is very well documented.

Ceylon has special language-level support for interoperation with dynamically typed languages like JavaScript, and its module system even interoperates with npm.

Ceylon is indeed fairly easy and readable. Of course those ones who know OOP and a bit of functional programming concepts will feel almost at home right from the start.

HTML generation is supported right in the SDK.

If you don't use platform-specific features, you can reuse the same code in your backend server (be it in Java or JavaScript) and in your client-side browser code, for example for storing data, validating input etc.

The help system is designed to evolve over time; running update-help downloads the latest content.
When searching for help on items, you can simply type help commandname to get information about a command.
If you're not sure what you're looking for, but have a rough idea, you can search on partial command names, or even specify specific verbs to get a list of commands potentially of interest; e.g. help -verb write.
The information in help gives a good overview of the commands you're looking at, along with code examples, so you can see real-world usage without resorting to the web.

When calling a method with multiple parameters, rather than passing one variable per parameter you're able to "splat" one variable to the method, with the parameters taking their values from its properties.

Commands can be chained via the pipeline, allowing output from one to be cleanly fed as input to the next.

PowerShell is installable through Chocolatey.

The language can wrap and interact with code written in other language's, making it highly extensible.

Though Windows Powershell only works on Windows, the open source implementation Pash (http://pash.sourceforge.net/) allows the same language to be run on other OSes.