Mileage search part I don't like on any one world.
The rest of ba.com is very neat (might still stink if you want it to be. ;-). )
OW has a general problem with awards, such as cathay awards availability does not have a separate mileage booking class, but something their own system decides, so another airline has no way of checking. When calling AA or so, they will search manually and request availability by the concerned party.