As DRMW notes, "they can be very realistic on the high end."
Oh, boy, can they!
Handling is very realistic (including controls that work like RealSteel models) and high end models are far more accurate and have far longer ranges than most of the "springers" that most people think of when they hear "airsoft." Some of these models are EXACTLY the same dimensions and weight as their RealSteel counterparts.
It's not unusual to be able to shoot one ragged hole with 10 rounds at 20 feet; even 3" 20 shot groups at 50 feet.