As the major computer manufacturers continue rolling out their so-called Ultrabooks, Dell (DELL) has now joined the fray, launching the XPS 13.  Wall Street Journal  Personal Technology Columnist Walt Mossberg found the device to be built well and good-looking, but lacking the battery life that competing Ultrabooks offer.

In his weekly All Things Digital segment on FOX Business, Mossberg explained that Ultrabooks are what Intel (INTC) has been pushing as essentially the Microsoft (MSFT) Windows-based answer to Apple’s (AAPL) popular MacBook Air laptop.  They’re thin, light, offer solid-state drives, and when you open their covers, they come back to life (return from standby mode) quickly, Mossberg said.

The XPS 13’s screen is the same size as the larger of the two MacBook Air models at 13 inches, yet because Dell has managed to trim the footprint, the size of the laptop is similar to that of a 12-inch Ultrabook, but still has a good-sized keyboard, he said.

However, the battery life of the laptop leaves much to be desired.  "I think that is kind of the spoiler in this otherwise very nicely built, good looking, solid machine,” Mossberg said.  The XPS 13 is the "weakest Ultrabook tested so far and significantly weaker on battery life than the MacBook Air.  It got a little under four hours in my tests."

Mossberg said he’s been performing the same battery tests on laptops for about 20 years, and while users may be able to get five hours out of the XPS 13 under more normal conditions (his tests are rather rigorous), the laptop still gets an hour less than the best of the other Ultrabooks available and two hours less than the MacBook Air.

Starting at $999, Dell’s new Ultrabook comes out to $300 less than a similarly equipped MacBook Air.  However, consumers shopping for Windows PCs (Apple products tend to be more premium priced) are used to seeing machines at around $400 to $600, so that may be a turn off to them (the same goes for other Ultrabooks, many of which hover around $1000), he said.  Mossberg explained, it’s the solid-state drives inside these laptops (rather than traditional hard drives which are slower and take up more space) that drive the costs of them up.  Users who want 256GB of space, for example, will have to shell out an additional $300 for that upgrade, he said.