My limited experience with blue bikes is that they are heavy and are only 3 speed. They are fine for peddling around the city at low and moderate speeds, but I imagine you'd find them quite limiting if you were trying to do any serious mileage or got out anywhere where you could actually achieve higher speeds.

They are also time limited, so seeing them outside a 1hr ride from the nearest blue bike dock is a pretty good indication they have gone feral.