Until recently I had been a Gmail holdout. My wife uses it all the time, but since I have multiple accounts to monitor I stuck to more traditional email clients. But because I switch between computers frequently, I finally decided to give it a try. One of the first problems I had is that I didn't want to stay logged in all the time through my browser. Fortunately I had run across KCheckGmail before. After a little trouble getting configured, I finally got everything running and KCheckGmail gave me everything I was looking for.
sudo apt-get install kcheckgmail
The next step in configuring KCheckGmail to access your account. When prompted, I chose to have KWallet manage my passwords.
There are three sections in the configuration dialog. The first is login credentials. This is where you enter your username and password. Be careful with this page. Whenever you go to it, you password is always displayed as three asterisks. I've had problems with the correct password getting saved if I changed another setting. If you get a login failure and can get to Gmail directly through a browser, try coming back here and resetting your password.
Next up is the Network section. Here you can set how many seconds must pass between each time your email status is updated.
Finally, there is the Behavior section. I have it set to launch Gmail whenever I left click on the icon in the system tray. By doing this you are essentially creating a bookmark from the icon. The other major feature on this page is associating which browser to use. Your choices are the KDE default browser or setting a path to an alternative one.
I have been very pleased with KCheckGmail and will continue to use it. It doesn't have many features, but it is simple to use and accomplishes its goal quite well.