The PSP has always been an interesting handheld device since it's debut in 2005 with the original 1000 model. In addition to it being a gaming platform, it could be used to watch movies, listen to music, surf the web at an available Wi-Fi access point, and other things that Nintendo hasn't added to the DS. Like the DS over the past five years or so, The PSP has also made some hardware changes and upgrades since the original model. The 2000 was a bit slimmer, and the current 3000 has a screen that helps playing games a bit more manageable in sunny situations. Those two models essentially stuck to the formula of the original PSP: a gaming device of which has a multimedia functions. As for the alternative model, the PSPGo, I feel as though it was created based on the formula of a multimedia device that can also play games.
 
It's apparent that the PSPGo does not appeal to many if not most gamers. Sony decided to make the Go a more portable system by eliminating the UMD slot. This made certain games that are in the PSP's UMD library unaccessible to Go owners simply because they're not available for download on PSN. The is the biggest set-back for the system, because the predicted majority of the PSP user base own a considerable amount of UMDs and aren't willing to exchange them for digital downloads. I myself am a part of the minority of which have never owned a big collection of PSP games, and have for some time owned the main model of the system, so the lack of a UMD slot was somewhat irrelevant. But after my 1000 broke down a few months ago, that component become relevant because I couldn't play some of the games that I wanted to play, including Kingdom Hearts: Birth By Sleep.
 
As a posed to the PSPGo being competition to the Nintendo DS, I've always felt as the the Go was made to compete with the iPod Touch. There are videos on YouTube of it being compared to the iPod Touch, and the typical synopsis of the comparisons is that the iPod touch is good for general portable entertainment (music, videos, and casual games), while the Go has a bigger emphasis on gaming. Since the Go is scoffed by the PSP use base, it being frequently called a "niche" on EpicBattleAxe's podcasts last year, I think it's fair to say the PSP Go wasn't truly meant to appeal to the main user base. In fact, I remember that being said by Sony at their press conference at 2009's E3.
 
Again, I am a part of the minority of PSP owners that either have never owned a lot UMDs. I used my PSP 1000 more for music than games, but that has had it's problems because of it's size. The PSPGo on the other hand is why less bulkier, making it less of a chore to have it in my pocket. It's bluetooth functionality is pretty useful, and I eventually bought a bluetooth headset for $40 on Amazon.com, which actually saves me money because my wired earbuds would go def in one ear after two or three months and I have had to spend 15-to-20 dollars for a new pair. And the ability to pause the game, do something else with the system (mainly turning it completely off to save battery life), and being able to go back exactly where I left off is very useful when I feel like playing Chains of Olympus before class starts and I'm not close to any save points yet. Those three features are great for how I use a PSP, which are the reasons why I justify owning one. But I am aware that those three aspects of the Go are overshadowed by the fact that it's a gaming device, and that it disappoints on that front due to a lack of support from Sony  Go not being able to play UMDs, thus not having everything available to the system.

With all things to consider, PSPGo is a niche product the appeals to those who want a multimedia device that can also play games. Sony experimented with the PSP and got mixed results out of it; some like myself enjoy it while most don't care for it. Compared to the majority, many people seem to agree that the system is a flop of which not many people have interest in, myself included as the con outweighs the pros to some extent. Hopefully Sony remembers to put the gaming aspects of a potential gaming device first while developing the PSP2.