I'm new to cycling too, and I went with the Shimano 105 SPD-SL pedals. I did the recommended practice between a door frame, tried unclipping once, and it was very intuitive. Went out on the road, and had no issues clipping in/out. They felt like I had a very solid connection to the pedals, however, I obviously can't compare that to a SPD pedal. The walking part is definitely a bit awkward though. If I had to walk any significant distance, I would not want to do it in SPD-SL shoes. For me though, I knew going in that I wouldn't have to walk any real distance for what I want to use the bike for, so that's not a significant issue.

I haven't tried using the pedals with sneakers, although they probably are big enough to be doable, I'm not sure how stable it would feel though.