Some of, if the the most challenging caches I have been to have been Micros, now don't get me wrong, I haven't found that many caches however Geocaching is for everyone with many different tastes, not just those who want to climb that mountain or hike that trail. I have gotten a few friends into GeoCaching because of Micros, they find one that is well concealed or has some imagination behind it and say; "Wow, that was neat". Walking around looking for Micros will eventually turn into hiking and climbing for them. Micros are a good stepping stone and a way to get those who would normally say; "I would go but I can't climb that rockface or crawl through that cave" to agree to come along and catch the fever!