Amazon refreshed its Kindle Fire line Thursday in a move that clearly sets the stage for a tablet fight with Apple. The online retailer put forward a compelling story on paper: full-fledged tablets for under $300 with more memory and more processing power than the first generation of the Kindle Fire.

To recap, Amazon released five devices Thursday. They released an updated Kindle Fire for $159 to ship on Sept. 14 and a new e-reader called the Paperwhite that will ship on Oct. 1 for $119.

They also released three models of the new Kindle Fire HD: two 16GB, 7-inch and 8.9-inch models for $199 and $299, respectively and an 8.9-inch Kindle Fire HD with 32GB of storage and 4G connectivity, for $499. The 7-inch will ship on Sept. 14, and the 8.9-inch will ship on Nov. 20.

The 4G tablet, it seems, was not available to demo Thursday and will be shipping in November. But reviewers had plenty to say about the other two versions of the Kindle Fire HD.

Reviews were glowing, but carried a theme that was true of the first Kindle Fire: the tablets are fine, but they’re great when you consider the price.

Over at Gizmodo, reviewer Kyle Wagner summed it up this way: “The Kindle Fire HD is staggering on paper. In person, it's... pleasant. Which would be an equation for disappointment if you forgot for a second just how cheap this thing is.” He also said that the software, overall, felt a little slower than Google’s Nexus 7, which runs Android’s latest version, Jelly Bean. Amazon has made its own variation of Android’s previous version, Ice Cream Sandwich.

Other reviewers noted that the software on both the 7-inch and 8.9-inch devices appeared to lag a bit — a problem that the first Kindle Fire also had and subsequently shed with updates.

In terms of hardware, there was nothing but good news. Slashgear’s Chris Burns said that the hardware is a quiet, but solid backdrop to all of the software and services packaged in the device, and that “Amazon appears to have once again created what may be a winner for the 2012 holiday season.”

Mashable said that the 7-inch tablet is so much thinner and lighter than the first Kindle Fire that it will “feel like a whole new device” and seems to have pulled a lot of design cues from Google’s competing Nexus 7.

The devices’ biggest selling point, however, appears to be the HD screen. The Associated Press’s Ryan Nakashima said that the screen “is such a major improvement that I can’t see why you would purchase the upgraded, non-HD older model, even if it means saving $40.”

The speakers, too, got high marks from reviewers including TechCrunch’s Jordan Crook, who said that the audio from the Kindle Fire HD’s 7-inch model sounds great and looks pretty good as well.

They “add a nice design flare to the Fire HD,” Crook said.

So, what if you’re trying to decide between this and an iPad? Well, it could be a bit early to say, since all the reviews so far are based off a scant few minutes with the device. But analysts say that Apple will stay in a strong position in the market, even with the addition of these cheaper tablets.

Shaw Wu, of Sterne Agee, said in an analyst’s note Friday that Apple “could see competitive pressure” but won’t be severely impacted because it has “structural and strategic advantages.” The new tablets, he said are stronger competition for Android and Windows tablets, which lack the same content ecosystem of the Kindle Fire HD models.

It could, he suspects, have an impact on how Microsoft finally decides to price its Surface tablets.

The company will have more pressure to make its tablet prices lower than $300, he said — much lower than expected.

“Initial press reports indicated a price point of $599, premium to the new iPad,” Wu wrote. “But we now believe it will likely need to price at $299 or lower to give it a fighting chance.”