Unfortunately, unlike the VAIO Z, the X1 doesn't have a removable battery. Also unfortunately, it doesn't hold up nearly as well. We were very disappointed by its score of only just over three hours in our non-intensive battery test, with the screen at 40 percent brightness and wireless radios disabled. Though this might increase by a little if you opt for the SSD, either way it really isn't enough, especially since this will decrease further when using Wi-Fi or 3G.
On the bright side, Lenovo's rapid charging claims hold up, with the battery easily charging to near full capacity in just over half an hour. However, if you plan to be away from a socket for more than four hours at a time, the optional slice battery becomes an essential rather than optional addition. With it, you should get around double the battery life (which played out in our battery test), giving you a full day’s worth on the go.
Unlike the hideously complicated attachment procedure for the Sony VAIO Z's external battery, with the X1’s it's simply a case of clicking the slice in and you're good to go. Releasing it again is equally effortless. However, it does add considerable bulk and ups the weight to 2.13kg, which hardly jams with the X1's ultraportable ambitions. Still, you can just leave it off for the daily commute and short stints, and only take it with when you know you'll be going on lengthy trips without access to a power grid.
When it comes to value, the ThinkPad X1 is difficult to assess. On the one hand, it's priced higher than many lighter ultraportable rivals, and based purely on specs, weight or battery life it's not the best of buys. However, unmatched keyboard ergonomics and excellent connectivity make up for a lot, while its mix of ruggedness (especially the Gorilla Glass-protected screen) and business features aren't offered by any equally light 13.3in laptop barring perhaps Panasonic's elusive (in the UK) and far more expensive ToughBook range. Basically, with the hard drive version of the X1 starting at £1054, it's certainly not as expensive as we might have expected considering its target audience.
If you're just looking for the lightest 13in business machine going, the Sony VAIO Z starts at 'just' £400 more (without its dock) and, aside from its lack of optical drive in that configuration, is just as flexible. But then its keyboard isn't half as good and its build quality markedly inferior, nor can Sony's business support structure or software begin to match that of Lenovo.
Lenovo's thinnest and lightest ThinkPad laptop yet is a dramatic mix of ups and downs. Its build quality is even more impressive than usual thanks to the addition of a Gorilla Glass-protected screen, its backlit and spill-resistant keyboard is by far the best to be found on any ultraportable, it offers great connectivity, good specs and plenty of features. However, the X1 is a tad large for an ultraportable, its average screen doesn't jive with its premium positioning, and its battery life trails 13in rivals by quite some margin. If these issues aren't deal-breakers for you, it's a great machine, but many will be better off looking elsewhere - even at other ThinkPads like the IPS-sporting X220.