Great build IMO, and best Noc build out there. After trying the rest of the top Nocturne builds I can proudly say that if you enjoy getting early game kills, and then carrying late game, this is the Noc build for ou.
Here are my scores.

http://i.imgur.com/jSvkS.png
http://i.imgur.com/VqaAO.png
http://i.imgur.com/rf6YW.png

I created an account here just to upvote you, kind sir!

I'm new to this whole game, and did a 'personality quiz' to find out what champion I may like best. It suggested Nocturne for me so I bought it, and I have not regretted it once. I've tested out several different builds, and this one has been the most attractive to me. I love the sheer amount of attack speed you get with this build.

Now, this may change as I get higher up in levels(level 11 currently), but as of now, the squishy factor doesn't come in as long as I don't try to instigate a fight first, though I have already won several 1v1s and even tore into 3 one time when I was pinned. I did actually survive that, but I'm going to just say they were bad players because I also got 20 kills that match too.

Anyways, only thing different I do is throw in a Youmuu's Ghostblade before the Madred's Bloodrazer. Madred is definitely great against tanky characters which they will be at their peak in the end game at 18. I feel Youmuu helps more in the mid game when the mid lane starts getting busy. It's active fits in line with this playstyle for me and can really help burn opponents in team fights.

Love the guide, and I hope I'm not being too bold in commenting!

I've played noc before but ive always had to play him with some form of defense, but ill try it out and +1 if it works well

I added the Ionic Spark because it gives a bit of health, and completes the perfect 2.5 attack speed. The AoE effect it gives was just an extra bonus.

And, to be completely honest, I kinda like watching bolts of lightning arc between people I'm trying to kill :3

It was a bit of a rush job, I wrote it an extra hour and a half downtime I had this morning before class :P I'm planning on going back and making it pretty lol

And Malice, it's a bit expensive, but I rarely have trouble getting to Madred's Bloodrazer and Bloodthirster. I've only gotten to Infinity Edge a few times, but I've never really needed to add it to the build.

Awesome job Tyler, pretty it up and stretch it out and your good.