The debut of five new Kindles is an “important launch for Amazon” as the online retailer continues to make it as easy as possible for consumers to use the tablets to buy more Amazon products, writes Forrester Research Senior Analyst Sarah Rotman Epps in a blog post.

“Amazon’s services are the core of its devices, and the devices enhance Amazon’s service: A virtuous cycle where Amazon gains an increasing share of consumers’ wallets,” writes Rotman Epps.

“And Amazon isn’t finished,” notes Rotman Epps. “In a Forrester survey of 4,650 US consumers conducted online in August 2012, 31% reported that they had a credit card on file with Amazon, compared with 18% that have one stored with Apple, and 5% with Google. That payment connection enables Amazon to roll out more subscription services — which we see as key to Amazon’s future success — and to offer new products like smartphones, which 23% of consumers we surveyed said they’d be interested in purchasing if it were available. What it means: In the post-PC era, services rule, and Amazon is getting quite good at offering what consumers want.” Read the full blog post here.