I was born in and grew up in Houston and made trips back to Taiwan to visit family, so I flew almost exclusively Continental and China Airlines or EVA growing up. All of these airlines used the board from the back to the front of the aircraft, so I was used to that. A couple years ago I started flying United due to trips to Singapore and Taiwan and E+. At first I didn't really get the zone system since I had only been on flights that boarded by row, but I do think it makes a lot of sense and is pretty efficient. It isn't a huge deal to me either way (then again I am only a 2P/Silver). I find it really difficult/pretty much impossible to get United flights out of Houston now, and my upcoming domestic trips are on CO metal.