I've been using my iPad 3G for almost a year now and I love it. Here's what I use it for:
- Personal/Work email and calendar
- Web surfing on the go (and on the couch, in the bed, etc.)
- Movie and TV show watching (it's a great rear entertainment center especially with this:
Original BMW Accessories : In-Car connectivity)
- Casual gaming
- Educational gaming
- Book reading with iBooks
- Note taking with Evernote and Penultimate
- Document reading and editing with Documents to Go combined to Dropbox
- To Do list tracking with Toodledo
- Blog reading with Flipboard
- Home movie editing with iMovie
- Music composing with GarageBand
- Etc...
The only thing missing for it to completely replace my laptop would be a decent version of Microsoft Office (Word, Excel and Powerpoint).
I carry it around almost everywhere I go and it is now fully integrated into my daily workflow. I couldn't live without it!