It is quite short, shouldn't be more than 8-10 hours your first run, assuming some fights don't trip you up too much. Replay value is quite good because of it, there's five difficulties in total; easy, normal and hard to start. Beat it on hard and you unlock the fourth one, deadly. Beat it on deadly and you unlock the last one, insane, and anyone who has played that mode, myself included can attest it lives up to it's name.
Playing: Resident Evil 4 HD, Muramasa the Demon Blade, Metroid Other M, Dragon Quest IX Sentinel of the Starry Skies. PSN: jext77