The Newton fit easily in a jacket inside pocket, though it was a bit heavy. One of my friends actually had his jacket specially tailored to hang well with a Newton in the pocket. It also kind of fit in a men's front pants pocket, though it depended on the type of pants you like to wear. Didn't fit well in a shirt pocket or a back pants pocket; you did need a Palm Pilot for that.
How important is that? Well almost 30 years later, HP still sells the 12C. And the margin is astronomical.
[http://www.amazon.com/HP-12c-Financial-Calculator-12C/dp/B00...]