The very fact that most tablets become virtually useless out in the sun, is a huge minus in the tablet category. None of the tablets, expect the Notion Ink Adam has the capacity to make itself readable under the sun.
So what do I go for, a tablet or an E-book reader? Check out the flowchart below:
Okay so now I hope you have decided what you need. If its a tablet, there are a million of them, and basically it depends so much on individual tastes and needs, that its impossible to recommend something for everyone. But generally speaking, iPad and the Galaxy tab are safe bets. Notion Ink Adam is a great choice but it will not have access to the Android Market. Or if you want a more customised tablet friendly OS, then I think its better to wait for the release of Motorola Xoom.
If however your choice is an e-book reader, read on...
There are primarily 2 major e-book readers in the market right now. The Amazon Kindle and The Nook (the Nook Color being the latest). Amazon Kindle has released a newer version a few months back and quite confusingly its called...the Amazon Kindle, again. It has a better contrast and a better battery life (almost a month of usage after charging once) than older Kindles, not to mention the faster speeds.
The Nook Color though is a different product altogether, its more of a tablet than an e-book reader. It has the capability to display "coloured images", has a touchscreen interface and the glare-free screen. (The Nook has been quite famously the target of various developers, aka hackers, who have hacked the device to run Ubuntu on it!) However these features does take its toll on the battery life of the device and its battery life is substantially shorter than the Kindle (many users report the battery life to be around a day at the most, which is quite unsatisfactory for an e-book reader).
Hence, Nook is more of a wannabe tablet and less of an e-book reader. But then again, if you want a really cheap tablet, maybe the Nook is your bet. Beware though, there arent many apps around, so forget about playing Angry Birds on this device (although I hear someone has infact rooted the Nook to run Angry Birds! But its not officially supported, so basically if you manage to brick your device, be ready to pay some hefty bills to get it back in running condition).
And finally, the Indian market has a few e-book readers as well. Most famously, the Infibeam Pi and the Wink. (Pi being the one immediately below this text)
But these e-book readers have their faults and that is pretty evident with a little bit of googling. The Pi lacks 3G and Wifi. Wink has the Wifi but I believe their 3G version will be releasing later this year. However one of the biggest positives of these devices is their ability to read Indian fonts/languages. Infibeam and Wink both have amassed a vast collection and wide range of e-books.
Finally I guess after going through everything, it all boils down to personal preference. If one is more into reading Indian texts, it makes little sense to go for the Kindles and Nooks. Again, if one is in pursuit of a quality product which will be your "gadget of the year", Kindle and Nook are irreplaceable.
(As for me, I have decided to go for the Kindle)