Maybe Manchester's not the best place, what with all the work going on, but I had no problems transiting T2 on a recent visit to the States. Security was thorough but courteous and polite and I was impressed with the speed in which my baggage was handled given that my flight ( US Air from Philly, which was pretty well fully loaded) arrived shortly after the DL 767 from Atlanta and a Virgin 744.
As efficient as the airports I used in the States - Philly, Charlotte, Memphis and DFW.