Information is power.

If I have played with a player for any length of time, I can tell with pretty good accuracy when they are calling on the draw, because they think they might be beat but want to call me anyway, or when they're slowplaying. You can't do that online.

Online now, I'm losing a bit of cash to people when villians act weak with a decent hand. It's good that I've been looking into a little bit more passive style of play, because otherwise it might just be very, very frustrating.