I haven't used stakes much. I had a bad expirience with stakes.

I was fighting Viking style against Mongols who ocupied my conquests in the near East (Antioch), from my fortress on Cyprus. After catching couple of stacks on coast and uterly decimating them using autocalc, I decided to play one battle myself. I brought nearly the same number of Yeomen arhers and bilmen (and some swordsmen I think. But half of the army were the archers). I attacked an army of 1.5 stacks, and started battle.
I dug myself heavily on a hill (I nearly completly sorounded the hill with stakes. Also hill was near the end of the map so my back was secure and I only needed a halfcircle of stakes). First stack came and I decimated them. All HA and most of the INF and Heavy Cav died. Then the othe half came. But I was low on arrows so i killed some of them and then ran out of them.

Now the problem was. Alltough I had a strong position and enemy had no more missile troops, I also had no missilse any more. And enemy refused to attack (my general died earlier when returning from chasing some damn Mongol archers which were bothering me, by running full speed into the stakes (I didn't know they could harm my calivary)). They could avoid the stakes but they simply sat there. In the end I salied and got slaughtered by enemy on open field. Since then I allways a.calc Mongols, and never rely on stakes. Enemy simply wont attack.