That bus stop is really handy. The only issue I had at that place (that was when there was free bus travel) is transportation from the terminal. Don't be fooled by the Heathrow Area bus map as published by Heathrow Airport - while there is a bus stop more or less across the street from the PI Bath Road (Nobel Drive), don't use that one. Not only is Bath Road (aka the A4) a dual carriageway, it's got a fence in the median strip precisely to stop pedenstrians from crossing the street, so that's not an option. You have to get off at Oxford Avenue (one stop further), walk away from the PI to the traffic lights, and cross Bath Road there (in two times).