This dumbbell biceps curl exercise done seated on an adjustable workout bench works the full-length and range of the biceps muscle. It's really good for building bicep muscle strength and muscle mass. It is of my favorite biceps exercises along with the seated biceps curl on the Hammer Strength machine. I prefer to do this exercise at a wide angle because it hits the biceps from a different angle compared to the standard grip that I will use say on the Hammer Strength machine or using a straight barbell. Also, for this exercise, if you use a standard grip your dumbbell weights may tend to hit your legs and limit your range of motion so that you aren't working the entire range of your bicep muscle.
This is a more difficult exercise to do at an incline because you are going more against gravity and thus have less leverage. I prefer to use an adjustable bench with a foot rest because I can adjust the incline to whatever level I wish and the foot rest provides me and my back with extra support. It keeps my body pressed firmly against the back resting pad and allows me to really focus on the biceps curl, especially when you are lifting the maximum weight that you can.
For maximizing muscle mass and strength I suggest you use the maximum weight you can and that you do about 8 repetitions.
For women looking more for toning and increasing muscle strength, I recommend lighter or moderately heavy weights with more repetitions. Combined with triceps exercises, this exercise is great for losing arm fat, flabby arms.
Another one of my favorite biceps exercises that I recomment is the seated biceps curl on the Hammer Strength machine or any other similar bicep curl exercise machine.