Yandex is one of the few search engines, who has the leading role in regional search (I mean Russia and some former soviet countries). The rest of the world has Google as the #1 Moreover Yandex announced recently that they are going to compete with Google in future. That is why they made yandex.com not so long ago. Yandex has its own complex search algorithm (more than 60 of algorithms and filters if talking literally). That is why black SEO hates it so much) Also it has his own indicator in addition to Google PageRank — quotation index P.S. And I am glad they are expanding globally as my studio has very good rankings in design related search at yandex.com
Yandex, Soso, and Baidu all have very well behaved website parsing robots. They all adhere to the robots.txt exclusion protocols, and I list well in all 3 for my terms. I don't get a lot of traffic from any of them, probably only about 0.04% out of all 3 of them combined, but we have to remember that mine is a U.S. based company/business and my site pages are all in English. All 3 of these search engines list my site in English, and I list well, #1, #2, and #3 respectively for my terms. All 3 provide relevant results for whatever I search for.