The UI of a 2010 iPad could replace your laptop on trips. If you just need a device to occasionally keep tabs on email and review photos and bring up websites, the iPad has always been great for that.

If you need to do anything more intense, the one device you bring really should be a laptop, especially as we become able to engineer laptops that are increasingly small and light.

I don't think it's possible to develop a UI that is both as capable as a traditional computer and as simple and intuitive as early versions of iOS. The more actions you add, the harder any action is to discover.