First of all it’s a online application i.e access to gmail.com/google.com and add your email address, password to access different apps by Google. The improvements in the Gmail app is the sharpness of the interface making it capable for a Retina Display. Below is the comparison
Pull to refresh will of course bring up your new email rather than reloading/refreshing the page. The graphics are really cool for your eyes, feels very lite while using.