Gmail is one of the best mailing application till now as it has many feature it is fast and simple interface. There are good features and cons of gmail
Best features.
1) faster than any other application reliable and easy to understand interface.
2) can send upto 25 mb files on mail which is a really good thing none other mailing options provide this kind of file.
3) personiles label to sort your personal and official mails
4) attach multiple accounts to a single app if you are using multiple gmail account
Cons
1) you cant send multiple mails at a same time in gmail
2) you cant recall the mail if you bymistakely send it.
3) not ye ready for official mail