Today is the release of the free Beta of C3 and if you have not tried it here is the link:
https://editor.construct.net/
I gave it a try this morning and had a few problems getting the demo's to run until I turned off adblocker and enabled pop ups.
Then I tried a few of my current C2 games that don't have alot of events and no addons but couldn't get them to run.
Finally got one game that has only 20 events to run so I could test it a llttle and it worked fine.
Noticed some significant lag when I frst ran C3 and after posting a bug report I checked my platform settings and discovered I was running Chrome 32 which came on the 64 bit computer I purchased a year ago so I updated to Chrome 64 and that seems to have solved some of the lag problem so C3 was useful in that respect.
I have not tried designing a game in C3 yet and will probably try that tonight but if you have and you want to share your experiences or first impressions of C3 I would be interested in your impressions.
Try to keep it civil and remember this is a Beta test so bugs are expected for awhile.