Q: should i have restrictions enabled or disabled on iphone4

It depends on if you want to restrict anything. If you don't, I would keep them off. You can see more about restrictions in this article: About Restrictions (parental controls) on iPhone, iPad, and iPod touch - Apple Support

-AJ

It's entirely up to you. I have them enabled on my own phone, but it's just an added layer of security. The only thing that I have actually 'restricted' is in app purchased, because I don't want to make one by mistake, and changing account settings.