I love my 55 1.8 for the same reasons you list above, but beyond that, I have always liked the perspective of odd sized primes such as a 55 or 45 verses a nifty fifty. I know it's only 5mm, but on tight indoor shots that 5mm can really change the perspective. Especially when wide open on tight shots, the extra 5mm will give me tack sharp eyes but just a hint of softness moving out to the rest of the face unlike the real short depth of field I would get on an 85mm in the same situation.