It is much better then the old one, specially when they changed quite allot of things under the hood.
However, it is still by far away from what a normal laptop should be, here is the mini review I found out from a website.
So, before you get the wrong idea, you might want to read the MacBook Air review we did the first time around: almost all those caveats still stand. There's still one measly USB port, no FireWire, no Ethernet, a non-standard display plug (mini-DisplayPort instead of the equally obscure micro-DVI) a non-replaceable battery, an external-only disc drive with some odd power requirements and no internal 3G option or ExpressCard slot -- this is still a far cry from your standard, "full featured" laptop. Still, there's something about the MacBook Air, especially as a daily machine, that really shines through -- it's just so dang thin and light that you end up taking it everywhere and using it anywhere, and its shape is perfectly suited for slipping into a messenger bag almost unnoticed. It's the sort of portability that lends itself to lounging around the house, or boosting Starbucks cred, and it's a testament to that form factor that we've put up with the incredibly sluggish and fickle Rev. A for so long.
What's changed is that the frustratingly, mind-numbingly slow internals have been almost entirely chucked, to be replaced by a real grown-up processor, great NVIDIA integrated graphics, faster memory and a faster system bus for a dramatic speed boost -- Apple calls it 4x faster, and we can't really argue with that.
The dark ages...
We could comb over specs all we want, but what's really telling is usage scenarios. The primary problem with the original Air is that when put under strain -- especially video card-related strain -- it'd overheat to a point that it would shut down or at least severely throttle its weakling processor cores. At the start this led to completely-unacceptable stop-start freezing as the computer choked under even mild strain, but after a few firmware updates Apple got things down to just kind-of-unnacceptable -- though never managed to do as good a job of throttling and undervolting the processor as a certain 3rd party utility.
In daily use this usually meant that by your third or fourth YouTube video you were getting stuttered playback, and a bit more strain would result in slowdowns system-wide. Hulu or iTunes TV shows could rarely keep things going strong for more than five minutes, 3D games (even World of Warcraft dialed way back in quality) were out of the question and even significantly glitchy. Things would get exponentially worse if you were using the laptop away from a cold, hard surface, and instead plugged up the vents by using it on your -- gasp -- lap. Plugging into an external monitor was a particularly effective recipe for slowing the machine down to the point of unsuitability, and a day with the Air was a constant struggle to keep the right balance of tasks and locale to keep the temperature under crisis levels.
A coming dawn...
With Rev. B? Not so much. In fact, we've only managed to get the computer to stutter once, doing some particularly hefty HD flash video, after running on our lap (and destroying our reproductive chances) for the past hour or two. This also opens the laptop up to new possibilities like light iMovie editing -- out of the question with the original -- decent Garage Band multitracking, or a quick jaunt across Azeroth. Boot times are incredibly snappy (we're testing the SSD version, don't hate us), and the computer is generally a joy to use.
Since we're crazy enough to rarely use Ethernet, physical media or multiple USB peripherals, our two biggest remaining drawbacks are the fixed battery and the lack of internal 3G. With a shrinking chip and plenty of hollow aluminum, we're sure Apple could squeeze in some 3G if it tried, and it'd save us from using up that single USB plug so frequently with a horrifically awkward dongle affair. The battery is perhaps more serious. We'd say the average battery life with mild use -- about three hours, very much on par with the previous version -- is plenty acceptable, but for a laptop that so encourages portability, the inability to replace the battery means you can never be more than three hours away from an outlet, less if you want cellular internet. Lenovo, Voodoo and just about everyone else has figured this out, Apple needs to step up on both fronts if it really wants to get taken seriously by true road warriors, instead of some namby pamby bloggers (Paul Miller) looking to save their backs as they make the daily ten yard trek to the coffee shop -- or to the couch, if the weather's no good.
Overall, we'd say we highly recommend the MacBook Air to that particular sort of person who can deal with all the remaining caveats, but we really wish Apple had gotten some of this overheating stuff under control the first time around -- and that the firmware updates and compassionate Genius Bar shoulder shrugs wouldn't halt just because there's a new, trouble-free revision making the rounds.