Until now, of course, but I care about the future, not the past. I'm not talking about account security and that kind of stuff, but about they running with the money, or the website being an scam. I'm lending since like a year ago, and I'm very happy with the returns, but I don't feel comfortable enough to deposit more.
Look at trading and lending volume and their fees. I would estimate bitfinex is going to make at least 5 million in profit in 2015.
Given that this is a market with potential for explosion (the kind VCs salivate on) bitfinex is worth at least 50 million dollars, probably much more (barely profitable Twitter, after years of losses, is worth 32 billion...).
If the money on the lending market is the majority of all deposited funds (hard to believe it would be a minority), in addition to risking prison, they would lose money by stealing money. So no, it's definitely not a scam and they are not going to run off with your money.
The only real risk is theft by non-owners (hacking, disgruntled employee, etc), enormous losses from margin calls, their bank going bankrupt and similar. Same for all other exchanges.