Good... Coverage will be excellent, in fact better than 2G.. In future it will be better to use 3G only than 2G only mode to save battery (with data off).. But (data) network will get filled up quickly comparing 2100MHz 3G... So they may charge more in future, I guess... Still, people who are ready to pay premium for better coverage will go for it, imho..
Airtel is in idea of using 1800MHz for 2G and liberalised 900MHz for 3G... Things will be interesting when we find who are all the winners of 900MHz spectrum in current auction