Ubuntu has a proper way to upgrade between releases and you can upgrade from LTS to LTS with the update manager. With Mint, there is no official upgrade method, but you can just 'cheat' and change the source lists to the new release. it's not guaranteed to work but I upgraded from Mint 15 to 16 with this method and I just upgraded to 17 using this how-to.
First I upgraded my main desktop, a Dell Precision 390, it took a long time to download all the updates but it went fairly well. For some reason the English (UK) settings seemed to be missing after the upgrade, so my keyboard was set to English (US). Pretty easy to sort out in the Settings Manager. One thing that's slightly annoying is that Gmusicbrowser's icon will not show up in the Notification area anymore, despite that setting being enabled. There are also some spurious errors on boot but they do not hold up the boot process or cause any problems. The settings manager has been improved, Nemo file manager seems to have some refinements, and the system as a whole does feel a little quicker. There's a full list of new features on the Linux Mint website.
My HP nc6320 laptop upgrade went well too without any problems what-so-ever and, unlike on my desktop, the keyboard settings remained as English (UK). As you can see from the screenshots, my preferred configuration on laptops and desktops is to have a top panel and a dock instead of a lower panel, with Conky for system info to one side of the desktop.