Overall, the agents from India are not all that bad. The biggest issues that have plagued not only UA, but every other businesses that use csr agents from there, is that it has been very difficult to convince agents there to bend or break rules when necessary. In the USA, if we do not like/agree with a rule or have a special circumstance, we call back, demand managers, and eventually if we are persistent, will get someone to break or bend the rule.
In India, (and other British influenced cultures) if a rule is in place, it is generally culturally unacceptable to break it for any reason. Why would you want to? To convince them to break, bend or take control of a situation is one of the largest issues most companies face doing business there.
So that, the slight pronunciation issues, combined with the perception that the workers there are making wages in the sub dollar per hour range, generally creates some animosity from US callers - but overall they are actually not all that bad.
Some would argue that the culture of not breaking rules helps the bottom line overall as well. - But that is a discussion for a different thread...