Hey guys,
So the Oblivion PSP builds have been finally leaked.
Please understand that I can't talk about where I found them, you'll probably be able to find them within a few hours everyone on the internet. I do not know who leaked this and I'm NOT the owner of those game builds.

So, I thought I'd share my thoughts on the 5 Oblivion builds so far:
The Set-Up:I didn't manage to play every build in its entirety. Thanks to random crashes and freezes. It actually requires a lot of luck to get through an area. I'm using a PSPgo with 6.60 PRO-C2 CFW, extra CPU and RAM enabled, as well as using the UMD M33 driver.
Unfortunately any version of 6.XX LME X.X didn't work for me and caused a black screen after staring the games.

Surprisingly there's a lot of content in those demos, I wonder how far in development the game was, before being cancelled. Kotaku reported about rumors of Climax cancelling the title in August 2007. It's very likely that the latest 2007 build even might one of the most recent ones, before the cancellation happens. The released screens of the game confirm that, as all shown locations are present in the demos.

Back to the game -> the submitted build, along with another two are very different from the two latest ones. I'd go as far as claiming that that's when the rumored engine switch happened. In the latest builds essentially all important features of TES IV are present in the game (except sneaking which only works in the first two builds).
Gameplay:The gameplay is actually excellent for a game in first person view. What many probably won't realize during combat is that
the L shoulder button automatically locks the camera onto an enemy, so it is possible to move around and strike/block dynamically at the same time. Making magic and a bow/ arrow combination an effective and viable way to play, despite the restrictions of just one analogue stick.
Leveling up and allocating skill points is possible as well and works just like the PC and console version - at least in the two latest builds.
If someone is trying to complete the most complete builds, I'd guess we're looking at about 3-6 hours of content. There are some hidden rooms to explore and extra gold chests here and there.
The story is ok and very Elder Scrolls like and mostly revolves around the mages guild, which is expected since the game takes places in High Rock. While Anticlere and Glenpoint are cities known to the TES universe Rhalta and the prison where the MC wakes up are not. The mages guild is also located in Rhalta, along with their mysterious crystal cave - which is home to a glowing green crystal.
Lore-wise I haven't exactly found anything worth mentioning, while the architecture of High Rock is a very interesting bonus.
PRO TIP:If you feel like experimenting and obtaining weapons, spells and other items from the start -> simply go the character stats menu and hit the square button. A goodie bag will drop. Hitting the square button 1, 2, 3, 4 or 5 times spawns another goodie bag with other very useful items. Please not that you can't have more than 9999 gold in your inventory! Also armor isn't working as of now and makes your character invisible.

Final Thoughts:
I could go more into detail about several cool things I've noticed but I need more days or even weeks to get a good feel of every build and content differences.
After all Oblivion on PSP is a large scale game. I wouldn't have thought a portable version of such a large scale RPG was even possible, especially on limited hardware like the PSP.
This game is legitimately fun and in my opinion a outstanding technical achievement on the PSP hardware, even in such an early state. The game (file) size, content and quality prove that this easily could've become a benchmark for the platform and one of the most successful titles on the console. Of course that doesn't matter if the title wasn't profitable to begin with or simply a risky financial endeavor for Zenimax.
Send me to Oblivion if old.