I use a pair of 10 lbs ankle weights. They are great for adding resistance to your workouts. I would not suggest running or a lot of jumping in them because I have heard they add more stress to your bones. But overall for like pull ups, squats they are good to up the intensity.
The biggest problem i have with ankle weights is that they make it alot harder for you to keep your ankles in the correct position. The ankles will collapse alot faster usually. And wearing them before you have developed a good moving pattern makes it alot more likely to create a moving patterns with the ankles and/or feet collapsing and bringing the knees in a wrong position.
So basicly ankleweights can be used as a tool. But use them wisely. Specially with movements like squats or lunges they dont add weight to the lift but make you more likely to move incorrectly.