You speak as if the 3D is intended for watching films with... the reason for the 3D has always been games. Not only that, but if you turn the 3D off, the battery lasts longer so I don't understand your problem with it. If you don't like it, turn it off and then you have the battery life the 3DS would have had if it wasn't 3D. And by circle pad I assume you mean the circle pad pro. The circle pad is something that every 3DS has built in...
OK. The whole movies thing is a deal with the Hollywood. And Hollywood ain't cheap you know.
Indeed, you can turn the slider off, but the graphics chip used to power the 3DS continues to put a big strain on the battery. A graphics chip without 3D capabilities wouldn't put that much strain on it. Just to prove my point, the 3DS duration for DS games is at max 8 hours, whereas the DS Lite and DSi XL could reach double that amount.
And yes, I do meant Circle Pad Pro. For a moment I thought that Circle Pad Pro was referring to the XL edition, but then I found out it's called Circle Pad Pro XL. Damn, it reminds of a Street Fighter game.
Except that the 3DS has now sold MORE than the DS in the same timeframe, after it got its price slashed (the original price was bullshit, the new price is more in line to expectations!). The battery life of the 3DS was lesser thant it should have been, but it was still considerably better than the vita's. So, the 3DS is anything but a disappointment. Original price + underwhelming library caused a slow start, but a lower price point and a very strong (seriously, the thing has some great things out now) library have caused it to perform considerably better.
Sorry, but not anymore. Nintendo used to happily claim that the 3DS indeed outsold the DS, but that's no longer the case. Check the NPD numbers if you don't believe me. Also, comparing it to the Vita doesn't do it any favours. It's like comparing whichever of those two is a lesser disappointment. (It's the 3DS but you get my drift)