From what I've seen so far, it looks like a good mix. Awesome items can drop as loot but there are some equally awesome items in fixed places. The Cryonator for example. I also came across an amazing melee weapon that I can't get yet. Legendary enemies drop the best loot (obviously) but their appearance rate depends on difficulty level. IMHO, it's the best of both worlds.
I've only found one unique weapon so far, so I'm not sure if the same can be said for all others but it has an asterisk displayed next to it's name.
Big Jim* is how it shows up. It's a wrench that I've attached a very sharp spike to, and it's incredibly fun running around with it being soaked in blood.