As far as we know, there are no known issues with PHP 7. Deprecated warning messages are fixed in 3.5.8
Daniel, could you check the following because i can't:
PHP 7 RC 5, with GD lib enabled (since imagick is not available for some reason).
I try to upload a 2.5 mb image and fails with the error "File Empty". I can upload smaller images. The size allowed is 8192 within Osclass and 50 mb within PHP.
Not sure this is an Osclass problem or some setup with PHP 7 and RC.
Could you test a bit uploading large images, if you have some spare time.
Thanks !