I agree that posting on forums is a pain on the iPad, but I still do it because I no longer want to either go to my desk or move my MacBook to the sofa for something like this. In fact, there are whole days where I don't switch on the MacBook.
Creating visual content seems to be easier, though of course there are limitation. I've been sketching a lot on the iPad, I must have bought every sketching app on the market, LOL. It's fun but the image size is limited. I think it can also be used for basic photo editing: cropping, adjusting levels, resizing and posting to the web. I bought an app last night called Photoforge that seems to do all this rather well, although I prefer the clean and well thought-out interface of the Photoshop free app, but unfortunately it lacks some essential functions such as levels.
I don't know yet if I will use the iPad much for photo editing, because that also raises the question of managing the photos. I'd probably have to buy yet another app to organize them in folders and avoid cluttering the iPad's Photos app. Plus, I only have 16 Gb of storage...
Last night I wanted to make a simple spreadsheet and spent some time looking for a spreadsheet or office app, but looking at reviews none of the available apps seem to be good value for the money, so I downloaded Documents free which is very very very basic but OK for what I needed to do.
Still hesitating on whether or not to buy Pages...