I've been playing since pre-release and am still on my first run.
250+ hours in, 43 pairs of boots worn out, 3,000+ deliveries, 2,100+ KM traveled and I still want more. I'll likely get 3 months out of this first run.
Alternatively you can beat it in about 40-50 hours.
5 hours is enough to get a feel for things and since DS2 starts off with a bang rather than a slow burn like DS1, I'd bet the demo hooks a few people.
Remember to bring 2 PCCs with you at all times.