I've used this and have it as an APP on my smartphone. In my area, it is usually about 3 minutes behind (perhaps due to security). I found it more accurate in Europe.
Back when that plane was shot down over Ukraine, it was interesting to see the entire area devoid of any aircraft (as you'd expect).
I think there are differing versions of the APP (and the Android version isn't so good). I saw one on an iPad that was really neat; you could switch to "pilot view" (which was essentially using some sort of Google view). Nifty idea.