Ever since I download 5.0, not only did I loose EVERYTHING I had on my iPad, but my iPad is now horribly unstable, and will therefore force an app to quite mid-function.
I get similar unstable performance from the iPad after iOS5 update. The new operating system was clearly built with the iPad 2 and later devices in mind the A4 in my iPad 1 is having problems keeping up with whats being asked of it. I'm waiting until the rumour mill about iPad 3 spits out something creditable before I even think about upgrading as my upgrade budget is going on the iPhone 4s this year when it's released in my territory (Thailand) as both my current mobile phone is about to go the way of my old iPod 60gig.
The iOS5.1 update when it comes out will address allot of the stability issues but ultimately it comes down to the hardware.