Both my wife and I have iPads and ONLY since the upgrade to 5.01 have we suffered apps dropping out. We have manually tried to keep the memory usage as low as possible but it seems to make no difference. My iPad 2 colleagues do not experience this. I wonder if the developers have pushed to OS a bit beyond iPad 1? It is the only fault with a superb piece of kit - the most useful piece of IT I have evr owned.
I have iPad 1 and 2, both on 5.0.1. I'm definitely seeing more Safari crashes on both iPads since upgrading, especially on iPad 1. My diagnostics log shows repeated RAM crashes.
I think Apple has pushed the firmware to a point that it's disruptive to owners. If they were upfront about things, they would warn owners, so they could decide whether to upgrade, or give people the chance to downgrade. As it is, they leave customers with devices that are sometimes less functional after upgrades. That happened with the iPhone 3, for instance, and led to at least one class-action lawsuit that I know of. I don't think the claimants won, but I see this as poor customer service, rather than a legal issue. And I say that as someone who isn't sue happy and who has gotten a lot enjoyment and use out of my iDevices. My iPhone 3 became pretty much unusable after the last upgrade, because Web surfing became Web doggie paddling instead.
Given my experiences with iPhone 3 and now iPad 1 and 2, I probably will steer clear of coming firmware upgrades on iPad 1 and 2 if possible, to prolong their functionality.