I recently changed the screen on my Vader PSP. It was easy with a little dexterity and since there are still plenty of new replacement parts for all PSP models on the secondary market, I don't think I have to worry if and when something needs to be replaced (assuming the Vita thrives like the PSP).
I think that a Vita old enough to have to worry about replacing the battery in will have other problems before the battery. Basically it will be beat to he77 by the time that happens. You could also go buy one of those battery controllers and have plenty of battery without replacing it. I do wish sony would have made it so you could buy extra batteries that were easily swaped out for those times you don't have access to a outlet.
i had my vita for less than a year and now for whatever reason the battery randomly reads wrong and goes from full battery to saying the battery is low and then turning off completely. i realize this is probably a frak thing but its really annoying to have it barely be portable
I just took my Vita apart (it's easy, IF you can get the screws loose with a tiny screwdriver..... look up youtube vids) to see what battery was in it. Replacing the battery if you need to is very easy, and you can either order one off amazon (I could only find ONE listing with no reviews yet): http://www.amazon.com/gp/product/B00G5YW1AC/ref=s9
or get it off this site I found.... http://www.batterybuyer.com/2200-sony-vita-playsta
If anyone knows other listings for Vita compatible batteries (NOT on scambay... err Ebay) please post them. This eventually dies it'll be nice if we know where to go.
P.S. Vita snaps back together very easy as well lol ....