That's my worry :-) _just_ fine, or fine by a wide margin? If this thing dissipates 5W as is (without powering USB devices), I would think it gets fairly warm. 2 inch = 5 cm, so area will be 150 cm^2, or 0.015 m^2, or about 300W/m^2 = one third of summer sunshine, radiating out of what looks like a plastic enclosure.