There is nothing unique about it if you own a PS3.
The interface reminds me too much of a iPod/iPad etc.. it lacks that unique PS feel to it. The games are nothing special either. I really wanted to get this thing when I first heard of it, but now I've lost interest in it since the game titles...
I think Sony are smart enough and experienced enough to know what they are doing. They just came out of a huge hacking crisis and prior to that, the huge losses they incurred with the PS3. But look at them now, unscathed and making a profit. There is no reason to doubt Sony.
It's all wonderful and stuff but would I really enjoy playing PS3 quality games on a small screen or would I leave it to enjoy on my 50inch LED tv sitting on my bed holding a DS3? I'm not sure, I guess handheld is not for everyone even thought I used to be a massive fan when I was young.