I've used them several times from KSA to LOS and apart from their awfully borin' airport, I'd say they are very good.
Good quality 'planes, very pleasant staff and the food was always good. I normally order a vegetarian meal (means I get fed first!) and Qatar Airlines veggie food is very tasty.
They've always been on time and the connections on my flights have been very good, apart from once when I ended up with (I think 5 hours) in Doha, did I mention the airport was terrible!
i rate qatar as 1 of the est only flown once with them for £440 outof manchester england.a mate flew with them last october and he told me that they have new airbus planes now and u get ur own screen in front of u instead the over head screens.im flying with them at xmas got it for just over £600 for that price a couple of days before xmas is dam good.so make a booking quick if u find a good deal take it.