In reply to Mnelson:
You are at the mercy of the weather.
Your day could pan out as a strenuous walk with stunning views or turn into a fight for your very survival. But likely it'll just be a boring trudge in thick mist following other people that you hope know their way to the summit (and more importantly back down).
While sometimes part of the fun for the experienced walker is not knowing exactly what they are going to have to deal with, it may be dangerously difficult for those with limited experience to recognise when it's time to turn back before things get out of hand.
To be reasonably safe as a minimum you'd want to...
a) be able to navigate with map and compass in the dark / white-out conditions in order to not fall off the North face or into Five Fingers Gully.
b) have an understanding of cornices.
c) have and be be competent with the use of walking axe and crampons.
d) be carrying enough warm, water proof clothes / bivi shelter to survive in the harshest conditions you could possibly imagine should you become immobilised.
e) Have someone ready to call out Mountain Rescue should you fail to return by an agreed time.
