OK, to make up for all the useless crap threads with ill-informed speculation, here's something that will actually be useful.
Let me preface this by saying that I'm *well* aware of the differences between IMAP and POP (having supported hundreds of users with both) and absolutely IMAP is better than POP for many reasons that go far beyond the superficial ones that most people cite. However....
One of the most obvious advantages of IMAP over POP is that multiple email clients (say, your desktop and your iPhone) can see the same messages - If you 'get' your email on one device, you will 'get' the same email on the other device. By contrast, if you have POP'ed your email to one device, those messages aren't available to the other device any more (yes, I know you can do tricks with settings like 'leave on server', but that doesn't work in the expected way with GMail).
So, if you want to use GMail and make sure that you get the exact same messages everywhere (GMail web interface/your Mac or PC mail software/your iPhone), Google has provided a feature to make sure this works smoothly. Here are the instructions from the GMail help site. Just use recent:username@gmail.com instead of just username@gmail.com when setting up your GMail account on your iPhone, and it's all good.
Don't fall into the hype about needing 'push' email (edit: in order to see your mail 'right away') - just set your checking interval for 1 minute, and you'll never be more than 60 seconds away from your newest email.
(edited to clarify the last sentence)
Let me preface this by saying that I'm *well* aware of the differences between IMAP and POP (having supported hundreds of users with both) and absolutely IMAP is better than POP for many reasons that go far beyond the superficial ones that most people cite. However....
One of the most obvious advantages of IMAP over POP is that multiple email clients (say, your desktop and your iPhone) can see the same messages - If you 'get' your email on one device, you will 'get' the same email on the other device. By contrast, if you have POP'ed your email to one device, those messages aren't available to the other device any more (yes, I know you can do tricks with settings like 'leave on server', but that doesn't work in the expected way with GMail).
So, if you want to use GMail and make sure that you get the exact same messages everywhere (GMail web interface/your Mac or PC mail software/your iPhone), Google has provided a feature to make sure this works smoothly. Here are the instructions from the GMail help site. Just use recent:username@gmail.com instead of just username@gmail.com when setting up your GMail account on your iPhone, and it's all good.
Don't fall into the hype about needing 'push' email (edit: in order to see your mail 'right away') - just set your checking interval for 1 minute, and you'll never be more than 60 seconds away from your newest email.
(edited to clarify the last sentence)