One feature I'm particularly proud of is our code-less integration that lets you output to various services without writing against their SDK, saving lots of boilerplate code.
I have only played around with Lambda (so I'm not an expert), but I find Azure Functions to be much more streamlined. Lambda had a lot of really confusing options for URL rewrite, and I got really hung up with the fact that even site configuration is not saved until you redeploy. I can understand that behavior for reliability reasons, but they didn't show anything in the UI that showed that either the site or the config was dirty.
Obviously Lambda is more mature at the moment, but there are interesting aspects of Functions compared to them. For instance, is it possible to host a Lambda function on your own hosting plan (or the AWS equivalent?). I couldn't figure this out though the console, but I'm not an AWS expert.
We also have support for hosting Functions on an App Service Environment (ASE), which is your own dedicated set of VMs.
But, I'd like to from you what you like about Lambda and what you think of Functions once you have used it! What are your top 3 favorite features of Lambda?