I hated it.
Ruined the experience of drops.
You have a well rolled Calamity drop and it was like... "Hmmm... Is equipping this worth NOT selling it for $80+?" By not selling it you are essentially paying that $80 for it.
RMAH gave you two choices... Have a better game experience at the expense of free money or make free money at the expense of a better game experience. Both of them are shit. Should be about playing the game and grinding for better gear. Not selling gear for real money.
And now someone replies with "hurrr a durpp you could just ignore the RMAH!"... Yeah, with the ever present knowledge that you were throwing away free money, which ruined the experience.