I haven't used Yobit myself, as I've heard mixed reviews, and they don't seem to have great English support. But it seems that most of the altcoin exchanges are getting a lot of complaints these days, with Poloniex and Bittrex topping the list.
Yobit fits in the category of hobby exchanges that are purely being operated as a fun project ~ there is nothing serious about this exchange, and that shows in their volumes.
The far majority of the people making use of Yobit, are noobs chasing certain altcoins that other exchanges aren't willing to list. It also requires zero verification, which nowadays is becoming increasingly uncommon.
Obviously, there is nothing wrong with this exchange being operational since there is definitely demand for it, but people should accept the risks of certain things that potentially could happen with that exchange.
Poloniex is losing shine, but it's still far better than Yobit will ever be. Bittrex on the other hand, is the real winner in the last months ~ it gained a huge load of ex Poloniex and BTC-E users.