"Fire" is priced at $649 contract-free or $199.99 with a contract on AT&T Inc – a departure from the e-commerce giant's strategy to sell Kindle Fire tablets at near-cost to sell content tied to its ecosystem.
Walt Mossberg, writing on the tech blog Recode, said the biggest problems for the new phone were that it was only being sold on one mobile network and was tied to Amazon's ecosystem.
"Its unique features don't provide enough utility, and come at the expense of both battery life and performance," Engadget's Brad Molen said.
"Amazon's debut phone isn't bad, per se, but there's little incentive for anyone to switch carriers or platforms to buy it."
Amazon's shares were flat at $358.81 in late morning trading on the Nasdaq. The stock has gained 10 percent in the last three months.
