Decent. Lack alternative build paths.
Shatterglass can be good if the enemy has higher mobility than expected, or teamfights are quick.
There are many other situations such as those when you don't need Metal Jacket or Broken Myth.

Different build path for Blitz/BR, sometimes you might also need two boots with less defense. Yes, you might need 2 boots.
Eg: Lyra+Vox+Skye, and your captain can't afford War Treads yet.
You never know when you're gonna get bad team or bad draft.

All comments and suggestions, either good or bad, are always appreciated

I would also be extremely grateful if you press the +Rep button and upvote the guide :)