MehereThe benefit is knowing that you're wearing a piece of impressive engineering on your wrist. You also have something fun to look at through the caseback when its off your wrist. If you're purely looking for time accuracy then quartz wins out.
MehereReally there is no benefit. There are some things that make mechanical movements more attractive than quartz, but in general quartz movements are cheaper, more accurate and more durable. That said, the mechanical movement in this Seiko is highly regarded as a well-finished, accurate workhorse. You would have to spend several times the price of this watch to obtain a better, or even equivalent watch with a Swiss movement.
Aside from that, the design of this watch is just really admirable. It's nicely proportioned with a classic style and just a touch of Japanese aesthetic. I've had my eye on this one for several years, but I'm afraid I may be destined to admire it from afar.