The battery life is astoundingly low, with just less than a day of normal use - phone calls and a lot of Wi-Fi usage. This is quite bad for a 1200 mAh battery but a little easier to understand given the computer-like nature of the device. Still, it would've been nice if it could have lasted for at least 36 hours.
The greatest advantage this device would confer is to programmers - while the new ones can practice their skills on a powerful platform, the old ones have every tool they need with them wherever they go. At one point I was annoyed that the screen orientation would only switch between the right side and the standard orientation. However, one app install later, it was using the accelerometer to change orientations to whatever position I was holding the phone in.
The great part here is that the app was the thesis of some college student and had been given away since it was sponsored by the Google Summer of Code program. The GPS application Tango is pretty good, it's just one of many but arguably the better featured one. It can save routes, mark waypoints and shows your location as you move.
Maps for the app are downloaded as needed by default or you can download the entire thing, 400MB at max and just store it on your phone, all for free. This is what you'd probably want to do here in India where mobile broadband isn't exactly the cheapest resource and this in itself makes the device invaluable as a GPS tool.
The key thing to note here is that, as with desktops, Linux is only hard to setup the first time, once running, there's little that can take it down. Developers can make an easily installable package that the average user can just pop in or make it available through the repositories like a normal linux distribution.
Choice is a good thing but without standardization the common user might have problems with using it. That said, this is a dream gadget for a network admin, programming student or just about anyone in IT, especially since it functions just fine without a SIM card.
I'd advise the common user to get this phone only if they need one of it's unique features, like the open GPS.
Freeing the phone can have great benefits for users since all those minor things you think the phone will be able to do but usually can't are now suddenly possible. You don't have to wait for the company to get around to it as long as someone with the skills can fix it.
However like I said, if there isn't one of the device's unique features that you want, save yourself the Rs. 22,000 price tag and your IT savvy friends some distressed phone calls and wait a while till it has better support and a lower price.
Test unit sourced from: IDA systems