i have been reading its more like a 9mm on wickipedia any truth to that?
Steer clear of wikipedia for most of this.
You are going to find a wide variety of claims made, both for and against the 5.7.
Some will claim it's effective as 9mm, some will claim it's as effective as a .22WMR or even worse.
Both camps will use bits and pieces of what little data there is to justify their claims, and both groups will get very defensive if you challenge their position.
The round is likely somewhere in between. No one that says it is completely useless has volunteered to get shot with it I notice
The original round, the SS190, was used in many of the ballistics tests you will find out there. That bullet was designed to penetrate body armor and so it has very poor performance doing anything else.
Since then, several other bullet designs have been put into use and at least one aftermarket company is selling a self defense specific load.
I have a PS90 and a Five Seven. I would not hesitate to use them for self defense. However, they would not be my first choice at all.
But for the case of someone of small stature with recoil sensitivity I personally think the round is a great choice.
Shot placement is king as they say. I'd rather hit once with a 5.7 than miss 20 times with a .45.
With the recoil of the PS90 being practically non-existent it's a good place to start. Completely reliable, and 50 rounds so you don't have to worry much about training wives on tactical reloads.