Many models not really doing anything.
You have to not be too picky here in my opinion since you kinda take what you can get. Around 3/4 cams that I browsed through had a girl just sitting there, clothes on everything, mostly just wanting to chat and get some extra money. There are several with girls dancing, stripping, or dildoing themselves, and I even saw a guy getting sucked off by two women on one. So stuff is out there, but it's very hit or miss.
Quality isn't great.
Even the cams labeled as "HD" don't look all that great, and I honestly couldn't even tell the difference between that and a regular cam of theirs. The quality varies by performer, but I sometimes got big lags and buffering, with long pauses in the video being the norm.
No option for private one-on-one.
While it can be viewed as a positive, I think the lack of the option to take some girls private may be disappointing for some. You can have several jackasses spouting out demands all at once, and that may be a little too public for some people.