Internet is available free in Guatemala City everywhere from malls to restaurants and coffee shops. You can also buy USB modems from any of the local phone companies for around $25 to $50 if you select a prepaid service. Post paid services sometimes include a free modem, but charge from $20 to $40 a month.
3G/4G connection speeds are available in most major cities, edge connection is available in many other places.
Internet Coffees are not as common as there used to be in Guatemala City, and can usually be found only in small malls. There are many Internet Coffees in other cities and small towns.