I'm not saying that it's impossible or unfeasible to do actual work by using just an iPad. Many people out there manage just fine. What I'm saying is that it's unfeasible for me, for at least a couple of reasons.
Confession: I haven't actively used my iPad or Nexus 7 for weeks. And I'm ok with that.
Also, if you're not subscribed to Riccardo's site, you're doing yourself a disservice.