WMLongLife is an automatic 2G/3G band-switching solution. It will keep your device in 2G when you do not need to use 3G, and will switch to 3G automatically when you do need it. For most users, having your device in 2G uses much less battery, and thus your phone lasts longer on a single charge. 2G also usually generates less radiation than 3G, so it will likely be better for your gonads (if you have them).