Apple will start shipping pre-ordered iPad Air 2 units to its customers as early as Tuesday, but multiple technology publications have already received their own review units and the first reviews are already in.

All have agreed. The iPad Air 2 is, without a doubt, the best tablet available on the market. Unfortunately, even the best isn't enough for most people anymore. The iPad Air 2, which looks almost identical to its predecessor, is thinner, lighter and more powerful, with a faster processor, a better camera and the Touch ID fingerprint sensor that took a long time coming. Nilay Patel of The Verge calls it "a monumental achievement in the field of iterative improvement."

Patel praised the iPad Air 2's 6.1-millimeter profile, saying that "if there is anything magical about this new iPad it is this." Others agree. Joanna Stern of The Wall Street Journal says she can definitely notice the difference, and the iPad Air 2 feels like holding "nothing but a screen."

"It's not easy to build such a thin device that feels just as sturdy as its thicker brethren," writes Brad Molen of Engadget. "But Apple nailed it with the Air 2."

The thinness that everybody is raving about is due to Apple's use of a fully-laminated, optically bonded display that eliminates the gap between the LCD, capacitive touch layer and glass. This makes the 2048 x 1436 Retina display with reflective coating on the new iPad look phenomenal, but the technology isn't new. Apple has been using bonded displays on the iPhone since the iPhone 4 and on the iMacs as well.

However, Molen laments that Apple has sacrificed battery life for the thinner profile. Apple says battery life for the iPad Air 2 remains the same as the iPad Air because of the faster and more energy-efficient A8X processor, but Molen's testing shows "the new Air is 5.1 Whr smaller than the old one." In comparing the iPad Air 2 and the older iPad, Molen says the newer slate lasted 11 hours and 15 minutes of heavy use with Wi-Fi and data turned on, while the iPad Air clocked in at 13 hours and 45 minutes. On the other hand, the iPad Air Mini 3 lasted just as long as the older iPad.

Walt Mossberg of Re/code also posted the same observations, saying that while the iPad Air 2 exceeded Apple's 10-hour claim, the original iPad Air had "90 minutes longer" of battery life.

Still, there's no denying the fact that the iPad Air 2 is screaming fast. Harry McCracken of Fast Company thinks it weird that Apple, which didn't mention most specs for its new device, "isn't publicising (or even acknowledging) one of its best new features."

"The tablet now has 2GB of RAM, up from the rather cramped 1GB allotment in the original iPad Air," McCracken says. "Doubling the RAM means that the iPad can keep more apps and browser tabs in memory without having to reload anything. That results in a speed boost which is very apparent as you hop between apps and load new web pages."

Lance Ulanoff of Mashable also posted his Geekbench 3 results on the iPad Air 2. He found out that the new A8X processor, a modified version of the A8 chip running on the iPhone 6, has three cores. Ulanoff says the multicore score for the iPad Air 2 was almost two times better than the original iPad, but the singlecore score was only "slightly better."

"Apple isn't just blowing smoke when it says the A8X is more powerful," he says. "To get an anecdotal sense of the performance, I installed a pair of console-level games: 'Asphalt 8 Airborne' and 'Modern Combat 5: Blackout.' Each of these games is notable for rich imagery and physics including smoke, water, rain and reflections. The games looked and worked great on the original iPad Air and worked just as well - if not better - on the iPad Air 2."

Thinner, lighter and faster it is, but that pretty much sums up the improvements for the iPad Air 2. Stern is looking for a multi-tasking functionality where she could "see more apps on the screen at the same time, the way I can with a Surface or Galaxy Tab." She also criticizes Apple's aversion to keyboards and hopes that the rumored 12.9-inch iPad will finally bring more productivity features to reality.

Both Patel and Molen also noticed the absence of the ever-convenient mute switch, which was also sacrificed for Apple's obsession about feather-light thinness. Users can now turn on mute by going to the Control Center or holding the down volume button, which Patel says is not easier or better than having a dedicated mute switch.

Mossberg sums up what the iPad Air 2 missed: a higher resolution, a bigger screen, a change in height or width, better battery life, a snap-on keyboard and a lower base price. He also points out that Apple Pay for the new iPad is only available for in-app purchases and not for physical stores.

"They are, in most respects, the best iPads ever made," Mossberg says. "But for average users, they represent only a modest evolutionary improvement over last year's models, not the kind of big change that the first iPad Air or the Retina display iPad Mini did last year."

Most reviewers agree that owners of the older iPad Air might find it too expensive to upgrade to an iPad Air 2, which has a starting price of $499 for the entry-level 16GB model. Users who do a lot of video editing or, like Ulanoff, play high-end games on their iPad Air 2 will see the difference in performance, but Mossberg says most people who use their iPads for sending emails, browsing the Web and viewing videos won't likely feel any phenomenal improvements.

However, anybody who has an older iPad or is considering switching over to iOS from Android and looking for the best iPad money can buy, the iPad Air 2, as everyone says, is the best Apple tablet out there, though as Patel says, "it's not the best Apple product."