For concise info on ID, calls, breeding seasons & plumage etc. in a light, easily carryable package, the books by Grimmett, Grimmet & Inskipp and Krys Kazmierczak are good enough. Both these books cover a vast number of species along with nearly every plumage and form of these species, and are great for quick referral in the field.
However, I still love my 13th ed Birds of the Indian Subcontinent (Salim Ali). Like Sabyasachi says, although it covers fewer species, the info on each species is a joy to read, and it makes for better learning and understanding of bird life. Rasmussen & Anderton and the Ali & Ripley series are probably the best bird books money can buy, especially if you want to know more in detail.