In the same situation as you so I had bought a droid tablet. I have yet to bring it out in the field for a dozen reasons. I have had it for roughly 2 months and haven't had the time to set it up like I need it.
I was going to do a slide show of my clients properties....having a hard time with the slide show app not working right. Then I have had issues with transfering photos from my PC and other cell to the tablet.
I bought quickbooks online so that I could run mobile with my program for estimates,invoices & more. I have had a hard time transitioning my invoice template from my QB 2008 on my PC over to the online version. That has delayed use even more
Once I get all of these issues and more figured out I think it will be a great investment.
I wouldn't hesitate to get a Ipad or similar to replace a laptop. At this point they can do almost as much as any computer. It all depends on how much time you can devote to setting it up and keeping it up to date. Since everything I need is on my old PC I keep running back to using that seeing that im short on time and always in a hurry.