Backpacking in Central America is great, and backpacking in Guatemala is -- to me -- the greatest. (I even wrote a novel about it. More about that later.) The country is ultra inexpensive, populated by friendly people, and packed with so much beauty it overwhelms. The infrastructure for backpackers is also pretty fantastic, as long as they don't mind taking advantage of local transportation. Backpacker hostels are plentiful, and there's never any shortage of things to do.
Here's my list of the top backpacker destinations in Guatemala. The only one I haven't had a chance to visit is Xela, but I'm dying to go.