BDlot DVD ISO Master is a free tool which can back up any DVDs - protected or not - to standard ISO files.
Unlike some similar tools, the program doesn't require any third-party addon. There's no compression involved, or quality loss - the ISO file really is an accurate copy of the original disc. And it's very easy to use. At a minimum, you'll just browse to the source DVD, enter an ISO file name, click "Save As" - and that's it.
The program can additionally mount ISO files as virtual optical drives, though, for easier browsing or viewing. Which can be a useful ability in itself.
And it's also able to burn ISO files to your target file, again in just a few clicks.
Not a bad deal for free, then, but there doesn't appear to be a catch. It seems the authors are just hoping you'll consider upgrading to their more comprehensive BDlot DVD Clone Ultimate ($29.95), which includes extras like support for GPU acceleration, or deciding exactly which part of a video DVD you'd like to back up. Sounds interesting? Then the BDlot website will tell you more.