Nuts are high in fat calories. This isn't necessarily bad, but you gotta be aware. I eat a LOT of nuts when I'm on ketogenic diet.... Where you eat lots of natural fats & protein but almost no carbs.
Dietary fat got a bad reputation years ago & is still recovering. Many people still think fat is bad. Natural fats from food are a healthy component of any diet. Fat is calorie dense, so you gotta watch out if you're limiting calories, but don't avoid it just cuz it's fat.