I just think taking 70 points into unarmed is a MASSIVE investment and at that point well you might as well of taken unarmed for melee right? Its also a wasted stat if you use unarmed as your final skill well you cant put it into something more useful get me? Any melee weapon guys not take piercing strike? how does it perform without it?

Piercing strike is usefull for a few weapons and will be of a general help.

However a baseball bat and lead pipe with high-ish strength and 80+ skill will beat the DT of a giant radscorpian and can be achieved by level 8 easily.
The sledge hammer the next tier weapon is capable of beating most DT, the rebar club will go through everything I have found and the super sledge really needs no help I think.
Weapons like the ripper or chainsaw may need the help however, if you use these weapons it could come in handy, tbh though I don't know much about these weapons without the perk.
So go for it for role and the boost you get, if these don't matter find another perk that you like the looks of.

anyone else?

Melee fare fine without any Perk. Rebar Club and Super Sledge are very effective with Super Slam.

Once you get Super Slam and Slayer, all you need to do is make sure you can stack heal with various type of food.

You want it because of slayer 30% faster attacks outside of vats requires 90 unarmed. Combined and vs an armroed foe you will be doing alot more damage.

Yea, I generally take melee with unarmed. Also, to note, Slayer is a WONDERFUL perk. I love it so much. However, keep in mind that if you only want to put up to 90 in unarmed, make sure to take in account the skill books. I usually take Comprehension and only take skills I play to max (100) up to 86, that way I can conserve my points to be allocated elsewhere.

To add on to my point, I use knock knock for my melee which gives me a little distance between me and the foe. Because of this, I use it against enemies that tend to have a lunging attack so that I can keep them at bay (also works well agaisnt cazadores). Unarmed I use for up close and personal (using either Pushy or Love and Hate) cause you also get all the added perk attacks from the different NPCs that are specialized for unarmed.