Right now, I'm one of the few people who owns and regularly uses two different tablets. I do research and a lot of reading on my iPad 2 while my PlayBook is used more often as a media device and an 'on the go' browsing solution. At this point, the only reason I still use my laptop is the lack of a good Photoshop app.
The more time I spend using slates, the more difficult it becomes to tolerate using my laptop. There are no giant reasons I've stopped enjoying my laptop. But there are a whole host of little ones. I don't like using a touchpad to browse. A touchscreen is more direct and much less restrictive. It makes browsing a perfectly intuitive experience that you can lose yourself in. Both the PlayBook and the iPad have UIs that are easier on the eyes than something like Windows.
And, of course, there's the form-factor. I can lay down on the couch and do my daily research or sit in the bucket seat of a cramped van and work without trouble. Tablets fit everywhere. By comparison, most laptops take up quite a lot of space. And the ones that don't tend to be too sluggish to be anything but frustrating.
'Instant On' is crucial in my line of work. If you never know when you'll need to snap a photo or fire off an email or take down some notes, you want a device that can leap to action at the drop of a hat. The Chromebook's 8 second boot time is impressive, but nothing close to what a tablet can do.
I own two 12-cell batteries for my Toshiba laptop. Together, they get me around 9-10 hours of juice if I'm being efficient. My iPad 2 can hit 10 hours without breaking a sweat, and the PlayBook usually lasts around eight. Both tablets can go for hours and hours if they're just playing music.
Speaking of which- standby time is another big one. I hate opening up my laptop to find a quarter of the battery drained away from sitting on the sofa all night. I can leave my iPad in a backpack for days, flip it open, and find the battery level more-or-less where I left it.
I'm sure many folks out there do- and always will- prefer laptops to tablets. But I think that group will shrink further and further as the tablet "revolution" slouches onward.