A creature with menace cannot be blocked by one creature alone, which sounds like a small caveat and plays like real evasion in most games. Decks built around tokens, mana dorks, or a single defensive blocker simply cannot stop it. Against a wide board it is closer to a speed bump, since two chumps still do the job, but most midrange and control boards do not present two spare bodies on the turn the damage actually matters. That is the window menace exploits: not the late game with five blockers up, but the middle turns where the opponent has one threat down and is trying to develop another.
Mechanically, menace lives on aggressive two- and three-drops and on finishers that need a little help getting in. It pairs naturally with combat tricks and with anthem effects, because the keyword turns every point of extra power into damage the opponent has to either eat or double-block to stop, and double-blocking into a pump spell is how games end. It also makes a creature a much better carrier for auras and equipment, since the usual penalty of investing in a body that can be chumped goes away.
The honest weakness is that menace does nothing against removal, nothing against a single large blocker willing to trade, and nothing against the go-wide decks where two bodies are cheap. It is evasion priced for the common case, not the hard one, and it gets worse exactly when the game gets harder.