No, the client is not supported and yes it works with most of the features. In my case I used Jason Sandy’s startup script to get my client installed. Here is a few screenshots of what I have tested so far:

Client is installed and assigned

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The Application Catalog feature works

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Application and package deployment works like a charm

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Compliance Settings tested and working

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Inventory works

Software Update scanning works

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OS deployment works – just check the blog post from Johan Arwidmark - http://www.deploymentresearch.com/Research/tabid/62/EntryId/192/Beyond-unsupported-Deploying-Windows-Technical-Preview-with-MDT-2013.aspx