I'm using my iPad almost exclusively as my sole online/communication/data/entertainment device.
I don't have a computer in my home (but I do at work) and, so, no internet connection. The iPad's 3G is my connection at home.
Before deciding on the iPad, I looked at smart phones, but with the cost of voice+data plans, it made more sense for me to get the iPad. The Line2 app gives me a business line that can ring to my antiquated (dare I say it...) Tracfone.
My primary use for the iPad is for business (I'm leaving the IT field to become a full-time cabinetmaker). I'm using it for tech drawings, editing photos, updating websites, email, ordering materials.
I'd like to be able to do some simple bookkeeping on it, but I'm not fully satisfied with the apps I've seen so far.
I don't have a big need for music/media/games, but it's nice to have some good music or other diversions.
I researched it a lot before purchase and read all the cautions--"the iPad won't/can't replace your computer." Well, it's working fine for me.