Well, after months of forceful installment in my game, this is my experience:
Stages with the most nearby/well placed platforms usually give the opponent the opportunity to defend him/herself from this, unless that stage is Smashville, Town & City, Final Destination, and certain sections of both Castle Siege, or Delfino Plaza. I feel that primarily just Battlefield, Dreamland 64, and Lylant Cruise might give the opponent the most opportunities to avoid it due to how well placed the platforms are.
This tech is pretty much useful for primarily far away approaches, as the Metal Blade actually takes a wee bit of time just to finally stick out. You can use it close up, but it won't protect you from (some) projectiles and you risk the enemy interrupting it. However from just the proper space, this tech shines the best giving you far enough human reaction time to punish anything the enemy could throw at you.
Why is that? You cannot really shield it and even if you Power Shield it, there's a bit of shield stun lingering from the combo hit of the Metal Blade. If they do, its a grab. If they jump, then you can hit them with a bair, and of course if they attack, in most cases you're still covered against that. (Link's arrows, Samus' missiles, most jabs, etc.)
Your most primary follow up you'll want is: Bair, Up Smash, Down Smash, grab as they are the most consistent and serve most useful. If you can footstool to jablock and then infinite there from a raw metal blade, then that one would probably be most useful to you.