After reading countless 'bad' reviews relating to: small buttons (compared to the PSP 000 series); no back-wards compatability (i.e. UMD); too smaller screen (compared to the PSP 000 series) - and other negative comments in relation to a comparison to the PSP 000 series I thought I should write my first review.
I own both a PSP 2003 and a PSP go. As I see it, they are not supposed to be compared. These machines are designed for different purposes. Let me explain my reasoning.....
I use my 2003 as a 'Portable' - not a 'pocket and take with me' device. If I did, I'd constantly have to choose only 1 or 2 games to take with me and I know that as soon as I reach my destination I'll want to play the game I didn't take!
I use my 2003 for an hour each day whilst exercising on my bike (and if anyone wants to take me on playing Fifa after a year's practice each morning then feel free to get whipped! :-))
For this, my PSP 2003 is great. It doesn't have to be pocket friendly, I don't have to worry about taking my UMD collection, the buttons are big, the screen is the biggest available on a portable and it absolutely keeps me occupied whilst doing my exercise routine. For this use, and similar 'around the house but not tied to a TV uses' it is the best.
I use my PSP go as a 'pocket' device. I have 10 games on it without having to carry more than just the device. The sound is good, but thanks to the bluetooth connection, I can play with wireless headphones and not get tangled or caught on jacket buttons or other objects - also, I don't get that annoying reverberation of noise you get when you touch wires on sensitive in ear headphones. I use this when away on business, travelling on trains and buses and on holiday. For this use, and other 'on the go anywhere uses' it is the best.
True, media-go is not the most reliable software and you have to shut down and restart it sometimes to transfer a file....but with each version it is getting better - and I remember the early days of iTunes when it too was a bit rubbish!
Also true, digital only (PSN) games are priced by Sony and Sony alone and you can't take advantage of cheap UMDs or trade-ins....but then I have a PSP 2003 for this, and I never looked at these two machines and thought that they were in competition. They are simply different - and before the PSP go came along, I never used to take my PSP out the house as it was just too big and I didn't want to risk losing my game collection. If I lose my PSP go, I still have all my games on the PC.
So, in conclusion, I would say that they both are aimed at different markets. One is for the 'on the go' gamer that wants digital content and no luggage....the other is for the portable gamer that wants a bigger machine at the expense of not wanting to fit it in their pocket.
I would recommend the PSP 000 series for younger gamers - but that is because of the reasons stated above: Games are cheaper and can be traded in; and that they will use the machine in the house in the main (or their mates' house).
For an ipod user who is used to iTunes and truly wants a mobile games machine, I would recommend the go - even if the games are more expensive.
One final point, the current deal of 10 free games with the PSP go (until Sep 2010) is an excellent bargain - and worth buying just for that - but be warned, the 10 free games can only be used on the PSP go (before you think about using them on your PSP 000 series too) :-)