Hello, Pantsu Champion
Pretty much everything has been said in this thread.
Construct 2 doesn't really encrypt files on export so you can extract them when they're being cached (in the case of a web game) or from the files in case of a desktop export.
The protection is fairly basic, and code is much more protected than assets.
Some games have suffered from this as we said. I'm thinking of The Next Penelope by Aurélien Regard (that you can find on steam) that had its assets stolen and reused in a commercial project.
However, as Ashley said at some point, encrypting the assets doesn't prevent anyone from actually stealing them like in any other software as you can just grab them from the RAM or from the temporary files that are created.
This thread is a year old and since then my own opinion changed on the subject. At the time I thought that we really needed encryption, but right now I don't think that a powerful encryption is really that mandatory. Primarily because 3rd party software can offer the same kind of service for free (or not) and that in the case of stolen assets which can happen anyway the copytight protection services are there to help, like in the case of The Next Penelope where the game was removed in under a few hours.
When it comes to actual experiences, nobody ever stole any of my assets. Right now the only guy I'm sure had this happen to him is Aurélien Regard, but I recommend you try contacting developers from big Construct 2 games and ask them directly as this thread is pretty much dead and your chances of getting an answer here are pretty slim.