The benefits of a custom ROMThe most basic benefit of custom ROMs is getting rid of “bloatware” — the trial or otherwise unwanted software carriers often include in the ROM to get you to buy more stuff, that you may not need, and that takes up precious room on your device. When ROM “cooks” (ROM terminology often uses a kitchen metaphor, with cooking being a common name for the process of building a custom ROM) create a ROM, the first thing they leave out is the space-consuming trial software. They may also leave out many of the included utilities, letting their users add them back only if they need them. Often they also strip out vendor- or carrier-specific versions of the launcher, replacing them with Google’s original versions or a version they prefer.
Beyond simple fixes, custom ROMs can also open a whole world of new possibilities for your device. In many cases newer versions of Android are available for your device as custom ROMs, beyond what your carrier has released or is planning to release. The Viewsonic gTablet is a great example of that, with several different custom Honeycomb (Android 3.0) ROMs available for it, even though there is almost no chance Viewsonic will ever bother to try to port Honeycomb to it.
Custom ROMs can also include other cool features, like overclocking, themes, private browsing support, and so on. The gTablet’s Nvidia Tegra chipset, clocked at 1GHz “by the book,” can be overclocked to 1.6GHz with the right combination of ROMs and a custom kernel, with corresponding performance improvements. In some cases custom ROMs can even completely re-invent existing devices. There is already an alpha version of an Android ROM out for the HP Touchpad, a webOS device, for example.