Jester is an interesting attack in that may be either a junker or a gainer, and this is fairly luck based. Prior to posting this, I reread the 2011 thread about Jester (somewhat comical now in how overpowered it was originally thought to be...except for WW who is of course a genius
Having played a bunch of games with Jester recently, I'm forming a strong opinion that the junking element is far weaker than the gaining. As an example, in this game
http://www.gokosalvager.com/static/logprettifier.html?20150707/log.50991563e4b024b832068abb.1436272606957.txt I get hit hard with curses from his early Jester and it's still not enough. Possible reasons why this may be true:
1. Hitting a bad card off the opponent's deck cycles it, which is good for them right now.
2. By the next shuffle, there is often a way to improve cycling or trashing, mitigating the effect of the junk.
3. The junking is slow (1 card per play of Jester) and takes up valuable 5-cost space as a terminal silver.
4. Hitting a good card, on the other hand, does exactly the opposite: skips opponent's good card, potentially slowing their deck up to an entire shuffle, while making your own deck expand at a faster rate
As a result, I think Jester is better used on most boards as payload in an established engine as opposed to an opener (of course numerous counterexamples could apply) or in conjunction with deck inspection to guarantee hitting a good target. Scrying Pool seems especially juicy here, since the rate of expansion in a SP engine tends to determine the winner.
Just some food for thought. Would love some insight from better players on this!