Nothing really, apart from 1) RCSI is a crapload more expensive than the others, so apparently some of their students feel a little hard done by. It is very expensive and may not be justifiably so, but in my opinion, they're the ones who chose to go there and shell out that dough. 2) The particularly bitter ones feel the need to spread their bitterness. Misery loves company. Unfortunately, some people don't seem to realize that you make your own happiness and success although some hardships/inconveniences may have to be overcome and surprises (pleasant or unpleasant) can crop up along the way.
RCSI-bashing happens several times a year on this board and it's always the same boring never-ending spiel. Get over it, move on with your lives and I hope you've found more happiness/success doing what you're doing now. Plenty of others enjoyed their time there, let newcomers find their own way and stop spoiling the good experiences they've chanced upon.