Like I already said, we do quite a few very short term (week or two) loans where it's 62% APR (assuming full usage).
I do invest in ASICMINER, but that's not everything. The current situation is that even if I lose an amount of BTC or assets equal to our current liability, I can still pay everyone back. The question comes down to trust, and you need to make your own judgment on that
It seems to me that everything is relative. If the going rate of btc loans are very high, then deposit interest can also be high. Also if 25% is unsustainable in the future interst on deposits can also drop. But as stated above, the bottom line is trust. And even if TF is totally honest, that doesn't make the service risk free. I'm a new user and so far just enjoying watching my tiny stash grow. If I lost it all, I'd not be happy, but it wouldn't dramaticly affect me either. Deposit at your comfort level.