How about James Mattis as Defense Secretary?

Anyone have any knowledge or evidence based opinions on “Mad Dog” Mattis’ as Defense Secretary pick?
I'll admit, from the few varied things I've read, that all in all I'm slightly comforted by what I've read about Mattis. Just might be who we need in there, considering who his boss is. Admittedly, my feeling is based on little information, but it's a lot saner on initial examination than that DeVos