Direct flight from IAH to Buenos Aires, Argentina. Flight was full. As usual the passengers getting on first take the overhead luggage space even if they are not sitting nearby. Very little assistance from flight attendants throughout the 10 hour flight. They are in the back chatting among themselves instead of seeing to passenger needs. They barrel down the aisle with the food cart knocking passenger's elbows and feet. When not serving food they quickly barrel down the aisles knocking the passenger's elbows and feet again. Gone are the days when passengers were treated with respect by the flight attendants. It's like we're a bother to them now. Few smile or chat. One attendant's hair was constantly in her face to the point she dropped our food trays all over the aisle. She nearly spilled my drink trying to serve the passenger next to me. If they would slow down a bit and take care not to jam the serving cart into the passengers seats, it would be better. It's not like they have to hurry with the food on a 10 hour flight. Seats are jammed together. Very uncomfortable trying to sleep on a long flight. Larger and more comfortable seats would be better. I'm dreading having to fly any length on airlines anymore because of the poor customer service. We are constantly having our seats moved or the plane changed when booking ahead and without notice. We constantly have to check our reservations because of this practice. Pilot was excellent and flight was perfect. Some turbulence but not bad. Did not have to wait long before take off as we some times do.