Been using DropBox since 2012 with no issues. Security tips above are worth noting. Also, if I use it to share large files with personal information of any kind, once the receiving person confirms they have copied the file to their own system, I delete the file.
One tip - the free storage you get on DropBox is good but every time you share a directory with someone new who is not a DropBox user, they increase your free storage. Managed to use it for a business for 6 years without paying.
