Structure wise it has changed.
I have just changed from 5.2 to 5.3, and now upgrading to 5.4
So for my code personally (from the upgrade guide):
- had to switch $key,$value from first functions to $value,$key instead (easy fix after searching the entire stack app/)
- upgraded external packages to 5.3.* compatibility. Most of my packages were 5.3 ready
- added name => 'Application_name' to config/app.php
- removed namespace routes to groups (it wasn't resolving properly due to namespace, and removing it made all my integration tests works)
- went from app/Http/routes.php to route/web.php, and had to change the bootstrap.php to reflect this
that is all.
My lumen is strictly for background process commands and API calls so far. All my tests went green and travis tells me same.
Next is 5.3 to 5.4. The only gotcha i see so far are the request which i will need to inspect. If you were to ask me what is the benefit, I'm not sure yet but according to Taylor, It will be new functions that I haven't tapped into yet.
If you are looking for "benefits" I would suggest to read "whats new" in 5.3, 5.4 that is API driven specific. As far as I can see, a lot of the major improvements are in blade where it is easier for vue.js to integrate. This however is an opinion of mine and not fact.