Effect is better than dirty rat, but it is way less tempo. So I guess very useless against aggro, because you could just drop dirty rat on 2 and be good, if you drop this on 3 against aggro you will just die
I dont think its that bad. it can force play's that loses tempo. just taking hunter for example it can force a hunter to play a secret or play one of their 3 drops they didn't want to play maybe its hits a hyena or that 1/1 wolf so they have to play them out without value if they want to keep them. it can also force out early board clears maybe it hit brawl while you have 1 or 2 minions out or a flamestrike maybe it hits Zephyrs and now they have to play it t2/3
personally i think it's better in agro than a control deck and it is a tech card so it playable in the right meta.
The card is a tech: you simply look over one of those articles which shows the top decks and evaluate the number of cards (ideally low costed ones) it can screw up. Inner Fire and Divine Spirit are two cards this really screws. When played on 3 if you can hit one of those your opponent screams profanities.
This card is worse than it seems, because it suffers from the same problem as cards that give something to both you and your opponent - you're one turn behind.
Say you go first and play this on curve. The most you could hit is a 2 mana card in your opponent's hand, even though you have three mana. If you're going second, this hits a three mana card when they will soon have four mana.
Even worse is if you and your opponent are curving out, it's LESS likely they have low mana cards remaining in their hand and you have a decently high chance of hitting NOTHING. (The coin is always an option if they still have it, which is also not very good for you since it's an extremely low value target to hit)
So this gets its most value being a late game combo disruptor in a control deck, and it MIGHT be ok at that, but it's slow at that too since it might just let them do what they were going to do anyways.