That S5 is quite significant, analyst Tim Bajarin of Creative Strategies said during the Acer press conference at the Consumer Electronics Show in Las Vegas on Sunday.
It looks like the thinnest and lightest, and it sets the bar for the rest of the ultrabook vendors.
The Aspire S5 has a 13.3-inch screen and is only 15 mm thin at the thickest point of the laptop, weighing less than three pounds.
The Ultrabook will be priced in the coming weeks and is set to begin shipping in the second quarter this year, Taiwan-based Acer said. The Aspire S5 will be powered by Windows and an updated version with Windows 8 will be released later in the year following Microsoft's release of its latest operating system.
We are committed to evolving this technology, said Acer chief executive J.T. Wang. By the second quarter of this year we will have four models of ultrabook and more to come.
The Acer Aspire S5 Ultrabook, while being the thinnest on the market, is not a laptop created to compete with Apple's MacBook Air laptops, but to meet demands within the market.
The real battle is not with Apple, it is with all the other vendors coming out with Windows ultrabooks, Bajarin said.
Apple will still do great with MacBook Air, but in the Windows world it is great news that five years after Apple set the tone the industry is finally getting something equal, he continued.
In addition to being the thinnest, Bajarin called the Acer Aspire S5 Ultrabook the first viable Windows equivalent of the MacBook Air.
Acer also announced plans to include a free Cloud service for photos, videos, music and documents for all Windows 8 and Android devices.