I get National Geographic through Zinio on my iPad and The Economist and Foreign Policy on my Kindle.
Delivery of NatGeo is a couple of days slower than in stores... but it's no big deal to me. The Kindle magazines are delivered on time. I really like all of those and would never go back to print (had many more delivery issues with subscriptions - and more delays).
The industry is still in flux and not everyone is getting it right... But I guess I got lucky with the magazines I read.