I think there is financial frustration, because some posts don't make as much as they used to, and even when you're not in it for the money, I suppose it is frustrating to see crappy posts getting huge rewards for no apparent reasons, while great posts with 100+ votes get $0.02. That doesn't bother me personally, but I can imagine it bothering others. All this in addition to the price of steem falling, which is making people nervous. I myself just enjoy looking at other people's photos and showing off my own, but I am still nervous about the future of Steemit as determined by the financial aspect.
Some of the frustration could have to do with what I try to address in this post about whale behaviour. One of the comments there made me comment here.