Hm; to me personally, one advantage is that I immediately understand the idea and usage method of their service, while reading the links you provided I can't grasp what they're trying to communicate, unfortunately.
Also, I know Lua and value it very highly, so seeing it mentioned immediately focused my attention.
Thirdly, "free" "unlimited" "renewable 7-day" trial sounds great, and $5/month for persistent does too.
I agree - the simplicity of the service is great. Can immediately see what it does.
For example do those other services come with storage? I can't tell.
For parse, it looks like you need to install a command line application. Not useful if your desktop is Windoz.
I doubt anyone is going to be building huge applications on webscript.io (yet!) but for simple little things (aka weekend projects) it should work great.
http://blog.parse.com/2012/09/11/welcoming-cloud-code-to-the... https://cloudmine.me/docs/servercode