I use the ipad as my main computer now. Desktop only serves as a torrent machine and media server. Also, from time to time, when I need to do some serious word editing/formatting, and have to use MS Word, or need to draw a new component from my DIY projects in Solidworks, I can't do that on the iPad, but those aren't even monthly occurrences, and I'd like to give iWork for iOS a try (can't convince myself to pay the $$). For everything else, the iPad does a great job.
In the morning, it makes it easy keeping up with the news, redditing, checking message boards.
I use the iPad as my practicing central hub (I'm a career musician). All my sheet music and method books are in there, all organized and easily accessible in forScore and GoodReader. I keep a practice journal in Notability. The option to attach audio files to each note is a blessing. Metronome and tuner are easily accessible, and I don't have to look for them for 15 minutes before I find them. GarageBand is enough to sketch some compositions. I'd like to be able to write sheet music on the iPad, and there's an app for that, but I'm not sure how good that app is.
I use the iRig Pre, and a condenser mic, all of them attached to a mic stand, iPad included. This makes a very portable and compact setup.
When I come back home, books, videos, games and music are all here in my hands, again, organized and easily accessible.
Being a mobile device it also means I can keep on doing all of these on the road if I need to, which is one of the main reasons why I got an ipad.
I got a 16GB model and I wish I had saved a little more and bought at least a 32GB, but I feel the price difference isn't justified. Oh we'll. Great device.