I flew a 722 back from Chicago to San Diego on the last leg of a flight from St. Petersburg, Russia in the summer of 1996. I'd started out in St. Petersburg, boarding a DC9-40 of SAS to Stockholm, then the next morning on to Copenhagen on an MD-83, also SAS. The plane for the transatlantic flight was a 767-300ER, packed from nosecone to tailcone, and somewhat cramped. Also an SAS flight. So actually, the half-full UAL 722 for the final leg was quite comfortable, never mind that the flight was some 4 hours in length. It is a pretty quiet aircraft, given the location of its engines, and I didn't find the seats to be uncomfortable at all. Given how tired I was after spending 15 hours in planes and airports, I am sure I would have noticed if it had been either loud or uncomfortable.
Of course, when it comes down to it, who wouldn't prefer a 757? >;-) But the 722 is a great aircraft, overall.