One of the more powerful Anarch tool's since it came out but has only gotten stronger as cards like Eater & Hades Shard have come into existence. It's power doesn't just come from trashing cards and avoiding actual access but also the amount of information you acquire about your opponents deck its likely if you get only 2 runs in you'll see a massive 4-5 different cards which can be enough to know what kinda deck their playing.
Keyhole also oddly works well with Medium as you still build up counters on medium with a Keyhole run & you can use Keyhole just to shuffle the deck allowing more new cards to be seen.
Can Trash cards that can't normally be Trashed
Get valuable information about your opponents deck
Works with Eater
2 can be difficult to spare
3 Influence makes it a little heavy to take out of faction though not impossible
Requires a way into Archive to actually win with the card.