When SPD road pedals first came out (maybe 15 years ago) the knock on them that I heard most often was that they caused hot spots because the contact surface was so small. You can compensate with stiffer soles or use pedals with larger contact surfaces. My pedals and shoes (also from that era) have both and I never had any difficulties. I've recently started riding again using all that same equipment and they pedals and shoes are just as comfortable as before. The issue comes up again because of the desirability of shoes that allow one to walk normally. This compromises the stiffness of the sole so that you have to go to a larger contact surface to improve the comfort. It is an individual thing and some people with the same shoe/pedal combination don't mind a bit. Fit and comfort are worth paying for if you can afford it. Speaking for myself, I'm too old to put up with less.
-soma5
Added in edit: hey, I just noticed that I'm a "junior member" here. That's pretty cool - it's been a long time since I was a junior anything!