Using observable or subscribe in angular 2 or 4

Services=> loginServices.ts

import { Injectable } from '@angular/core';

import { Http, Response, Headers, RequestOptions } from '@angular/http';

import 'rxjs/add/operator/map';

import 'rxjs/add/operator/catch';

import 'rxjs/add/operator/throw';

import { Observable } from "rxjs/Rx";

@Injectable()

export class loginServices

{

        constructor(private _http: Http, private _router : Router) { }

login(obj:logininfo) :Observable<logininfo>

 {   

     let _headers = new Headers({ 'Content-Type': 'application/json' });

     return this._http.post('http://localhost:53656/api/Login/checklogin', obj, { headers: _headers })

    .map((res:Res) => <logininfo>res.json()); 

    .catch(this.handleError);      

}

handleError(error:Res)

{
    console.error(error);

    return Observable.throw(error)

}

Controller:

import { Component,OnInit } from '@angular/core';

import { loginServices} from '../login.services';

import { Router } from '@angular/router';

import { FormGroup, FormBuilder, Validators } from '@angular/forms';

import { logininfo } from '../login.interface';

@Component({

  templateUrl: '../../UI/Dashboard/Login.component.html',

  styleUrls: ['../../Content/Css/master.css'],

  providers: [loginServices,logininfo]

})

export class LoginComponent implements OnInit {

msg:string;

info:any;

constructor(public _lservices:loginServices)

ngOnInit()

   {
       let data:logininfo=> new logininfo(); 

      this._lservices.login(data).subscribe(

       (logininfo )=>{

                  if(logininfo ==null)

                   {
                      this.msg="User doesn't exist"

                   }

                  else

                  {

                      this.info=logininfo;

                  }

       },

       (error)=>{

                 this.msg="Some problem with the service. Please try again after some time".

          }

       )

    

   }

}