I too have had recently very good experiences to from T4 at LHR.
An easy quick trip from Paddington station from the trains to the Line underneath.
It is very well serviced for access with lifts and wide open spaces on platforms and areas on board, especially for people with lots of baggage, and i noticed, disabled people. Good to see many local residents using stations in-between in both West and East London.
Even staying at LHR pre or post travels in one of the T4 hotels, it is very quick to access C or even through and up to North London.
However, i would be cautious as to the times i take the trains which are mainly after 10-3.30pm.
But on my use, i find it very efficient, frequent, and access friendly at the stations, much unlike the tube services, especially with luggage!
