I could NEVER go back to an HDD, but in all honesty I am used to super fast SSDs now. Some people, and I am thinking of my 65-year-old mom, wouldn't know her computer is not fast as it would still be faster than her old desktop... then again, they're all stuck to their iPads right now! Those "IPS" displays have my whole family wowing, except me. I love my retina display iPhone 4.
I don't know why, maybe I am a purest, but I cannot deal with an iPad that cannot fit in my pocket, and also cannot run apps I need like my MBA does, and also doesn't have a physical keyboard for me to type 60+ wpm. On the iPad, I might hit 20 wpm. So the iPad doesn't fair well against the iPhone/iPod Touch in portability, and it doesn't fair well against the MBA in capabilities... I like my setup...
MBA, Mac mini OS X Server, 27" iMac, 3 x 24" ACDs, and an iPhone 4! Honestly, the iMac is for "business" to type my book on at home (don't ask, it was a bargain, at $1269 refurbished, and I couldn't say no - and I wanted a 27" LED ACD). The Mac mini OS X Server is my "toy" for the entertainment system. The MBA is my real computer, and the iPhone 4 does everything on the go....
However, not to tell a lie, I have been cheating on my MBA with a Lenovo ThinkPad x301. I love it. It is perfection for typing on the go, but it's a "work" computer to take to clients offices. As soon as Apple updates the MBA with 4 GB RAM or more... so I can run Windows 7 in a VM, I will be back to the MBA full-time for personal and business use. I will probably keep the x301 for a long time though. It will run Windows, Word, and PowerPoint for a long time!