I see many valid pros and cons in this discussion. Its fun reading thru em considering how much of a bad rap the PSP GO had upon release and rightly so in some regard. Things have a way of working themselves out in the end and regardless if this system was a failure financially, im still impressed what it has to offer in such a small form factor.
For those worried about M2 Memory Cards and storage don't fret. The internal 16GB of storage is plenty considering it takes hardly anytime to transfer what you want with the Media GO Application. In the mean time scout around for a decently priced 16GB M2 Memory Card. I paid around $25 for mine on Amazon but that was 2 years ago. I see prices have gone up but im sure you can snag one on ebay bidding on one.
The D-Pad is decent but the form factor will as one user stated give you GBA SP cramps.
Battery life for me is average. A full charge lasts me about 4 hours of gaming with brightness cranked and bluetooth and wi-fi disabled.
I was able to buy the dock and a extra ac adapter, travelers case and screen protector on clearance @ TRU for barely nothing so definitely check.
If you want to pair this with a dual shock controller remember that six axis controllers work as well. These controllers are lighter than the DS3 since their is no rumble feature. They are also a pain in the butt imho to pair with the system so Its nice to have a dedicated controller solely for your GO.