1) It does not work with anything inside VPC. EG: RDS Databases cannot be used. This severely limits why you'd use this on AWS for larger apps.
2) Trying to get it working for a real app is a bit of a gun show. Debugging was a pain, you cant really write any unit tests easily that I found. Local development was confusing.
3) Lambda forces you to use old technology. Node .10x, Python 2x.
4) You're using code that will only ever work on AWS. If you don't like vendor lock-in then look elsewhere.
If you don't need VPC access take a look at Heroku and background workers. They scale independently from the front-end main app. No servers to manage, just git push heroku master. You can write them in pretty much any language you want. Heroku supports the latest stacks and languages.