You get 14 days to return it, if you're not happy. Those are around the average speeds that I get on Sprint. Worthless. If you have no promise of 4G LTE coming your way soon, I'd return it. Then again, even if they've promised it, Sprint's promises aren't worth much.
This is from their page. It's not the greatest return policy, but if you just bought the iPhone 5, you're well within the return timeframe.
Return it for a refund
We love our products and services, and we think you will too. With the Sprint Satisfaction Guarantee, you can try your new product for 14 days. If you aren't 100% satisfied with your product, return your device to your original place of purchase and contact us to deactivate service within 14 days of activation (day 1 of the 14 days starts when the phone is activated) or 14 days of purchase for accessories and devices purchased with no service plan (such as a wifi only tablet or notebook) and Sprint will:
Refund the device purchase price (as long as device is complete and undamaged)
Waive the Early Termination Fee (ETF) (as long as the device is returned)
You may have to return any handsets and accessories purchased with the service before your account will be cancelled. Customers are responsible for all their usage charges (included but not limited to Monthly Rate Charges, add-ons, casual or out-of-plan usage and related taxes and Sprint surcharges). However, if service is cancelled within 3 days of activation the activation/upgrade fee will be refunded. The 14-day return period starts the day the phone is activated in our stores, online or by one of our channels.
Gift cards and iTunes cards are not redeemable for cash and cannot be returned or exchanged (except as required by law).
