I am not sure that I agree with this post. Personally I do not find a 5 minute walk in a covered walkway from T4 to the Hilton a problem - I am by no means fit and just about as lazy as you can get, but honestly this walk is nowhere near as far as your average check-in to departure gate walk.
The Heathrow Express lifts are very close to the walk-way so I have never found a inter-terminal trip a problem.
Yes this hotel is designed for T4 passengers, but I would rather walk for 5 minutes than wait for a bus for 15 minutes, not being sure if it will arrive!
Nick