The carrier does provide other plans that don't require you to lock into a two-year pact. For example, paying $65 a month gives you unlimited talk, unlimited text and 2GB of data. Since there are no overage charges, the carrier slows down your data speed if you exceed 2GB of use during the month.
If you're within U.S. Cellular's service range, and are looking to go sans contract, you might want to consider one of these plans if you're not that heavy into surfing the web or viewing videos.
source: USCellular via Phonescoop