I trust your intuition.
At what casting cost would you play this and the other cards?
I think its because I'm a control player and not an aggro player honestly. If someone wants to pay 4 for a vanilla 4|4 I usually don't care at all.
Ambush as an ability scales weirdly in that its best on small low cost beaters, gets worse on midrange guys, and is theoretically easily controlled by the time its late game enough to worry about big guys. On the other hand fractal + smaller ambush guys seems like it can be retarded fast, and as a control player ambush on a weapon seems like it could be crazy. Its really hard to say where the balance should be.