As English is the one major, common thread between Qatar's multinational population, almost everything can be done in it. Depending upon what it is you are tyring to accomplish, a little patience may be in order while someone who speaks it fluently can be found to help you on your way. Most frontmen/women do have the multilingual skills necessary to complete a purchase transaction or to give you the information you seek. This, however does not hold true for the "Old Souk" where it is a good idea to have a fluent arabic speaking person along just in case. I have personally found that if one puts forth the effort to try to communicate, however badly in arabic, or one of the Indian dialects, (depnding on who your trying to communicate with) most people tend to not want to see you struggle and readily break into english.