I don't use Excel very much, but I do use it for relatively simple tasks. I have it on my iPad. I don't use it for more than updating one cell. Otherwise I go to my laptop.
I also have Word on my iPad. Use it to read documents only... Just refuse to do anything else because it is cumbersome. Unfortunately, it is a beautiful app and I'd love to use it more.
I DO use Onenote on my iPad though... Basically as a replacement for Evernote. It is plodding on the iPad, but I usually just update minor things that I've already created on my laptop.
All around very impressed with Office on iOS... Very unimpressed with Apple's decision to not allow pointing devices...
My experience as well - I do a fair bit of Excel and just "get through it" on my iPad and certainly don't do any complex worksheet creation from scratch on there - That would be my definition of "hell"