Still probably the biggest stumbling block is not having an application registration, I now have a menu that allows to you use various default registrations for testing and also to save a default registration that you create. This means once you have your own registration setup you can save the ClientId so it will be used as the default when you next use the module.
A failure in proper planning when I initially created the module meant I didn't use a specific alias for the cmdlets in the module which meant it can cause a lot of conflicts if you have other modules loaded. With the new version all cmldets have a -EXR moniker.
With previous versions of the module you basically would authenticate and create an access token and store that in a local variable which you then had to pass into each of the cmdlets using the -AccessToken parameter along with the MailboxName. This meant a lot of typing and really broke the useability flow without really providing any security benefits. With the new module while all these old behaviours are still valid there is now a Connect-EXRMailbox cmdlet which is the new entry point cmdlet which will store the token and the name of the mailbox associated with the Token in a script variable (encrypted of course) but accessible by the module. This means you can run most of the cmdlets without specifying a Mailbox or Access Token if you just want to return details about the current mailbox that has been authenticated. Also when it comes to using Directory or Reporting cmdlets it eliminates the need for MailboxName which used mandatory parameter on all cmdlets.
New Getting Started Guide
With this type of project documentation is the hardest thing as its the least interesting and more time consuming things to get correct. I've written a new getting Started Guide for people that haven't used the module before. The old readme guide is still valid so if your looking to use App Tokens this going to be useful
I have a lot of new cmldets most aren't documented in anyway but I hope to put these more into Context in the new year on the blog and on GitHub. Things like accessing the Reporting API's is interesting which I've covered briefly in the new Getting Started guide.
The new module Exch-Rest is available from the PowerShell Gallery here or the source code which will contains all the latest code is available on GitHub here.
Feedback and Contributions
As always I welcome any feedback or contributors who want to improve the module