Is it safe to allow non-admin users access to media uploader

WP is reasonably secure for default use cases. In typical workflow it will call wp_check_filetype_and_ext() to verify that file uploaded is of allowed type.

It can get considerably more questionable in regards to security if you customize it to work with non–default kinds of files and you might need to implement your own security checks.

Note that users with special unfiltered_upload capability will be able to upload absolutely anything at all, so be very careful if you are assigning it to any roles.