Angular2: unable to navigate to url using location.go(url)

Yes, for redirecting from one route to another you should not be using location.go, it generally used to get normalized url on browser.

Location docs has strictly mentioned below note.

Note: it's better to use Router service to trigger route changes. Use Location only if you need to interact with or create normalized URLs outside of routing.

Rather you should use Router API's navigate method, which will take ['routeName'] as you do it while creating href using [routerLink] directive.

If you wanted redirect via URL only then you could use navigateByUrl which takes URL as string like router.navigateByUrl(url)

import { 
  ROUTER_DIRECTIVES, 
  RouteConfig, 
  ROUTER_PROVIDERS, 
  Location, //note: in newer angular2 versions Location has been moved from router to common package
  Router 
} from 'angular2/router';

constructor(location: Location, 
            public _userdetails: userdetails,
            public _router: Router){
    this.location = location;
}
login(){
    if (this.username && this.password){
        this._userdetails.username = this.username;
        //I assumed your `/home` route name is `Home`
        this._router.navigate(['Home']); //this will navigate to Home state.
        //below way is to navigate by URL
        //this.router.navigateByUrl('/home')
    }
    else{
        console.log('Cannot be blank');
    }
}

Update

In further study, I found that, when you call navigate, basically it does accept routeName inside array, and if parameters are there then should get pass with it like ['routeName', {id: 1, name: 'Test'}].

Below is API of navigate function of Router.

Router.prototype.navigate = function(linkParams) {
  var instruction = this.generate(linkParams); //get instruction by look up RouteRegistry
  return this.navigateByInstruction(instruction, false);
};

When linkParams passed to generate function, it does return out all the Instruction's required to navigate on other compoent. Here Instruction means ComponentInstruction's which have all information about Routing, basically what ever we register inside @RouteConfig, will get added to RouteRegistry(like on what path which Component should assign to to router-outlet).

Now retrieved Instruction's gets passed to navigateByInstruction method, which is responsible to load Component and will make various thing available to component like urlParams & parent & child component instruction, if they are there.

Instruction (in console)

auxInstruction: Object //<- parent instructions
child: null //<- child instructions
component: ComponentInstruction //<-current component object
specificity: 10000
urlParams: Array[0] <-- parameter passed for the route
urlPath: "about" //<-- current url path

Note: Whole answer is based on older router version, when Angular 2 was in beta release.