This game got pulled out while we waited for folks to show up a game event last weekend.
I'd never played it before (nor even heard of it!) although most of the assembled group had so apparently it's a frequent "filler" game for them.
Ease of rules: Very simple and quick to catch on - on par with Uno, simpler than Coloretto or Fluxx. Requires some basic memory skills like a small "concentration" game. I imagine most kids 10+ could play easily, although perhaps not with much sophistication.
Strategy element: Subtle. You start off only knowing two of your cards. If they are extreme (like 0/1 or 12/13) then the choices are pretty obvious - you know if it makes sense to swap. But the unknown cards? Or middle value cards? That's when it gets interesting. Different people at the table employed different strategies - some more willing to do blind swaps than others. If you're following one of those folks, their mistake is your gain! But expect everyone else at the table to be watching that exchange, since now they know where a desirable card is.
I fared poorly initially, not knowing how important it was to figure out the unknown cards. I also didn't have a sense of when it was safe to call "Cabo" and expect that my cards were the lowest. After several rounds, you get a feel for how long it takes for hands to shape into something worth competing with. Luck plays some factor with any deck of cards, but the more times around the play goes, the more strategy takes a role.
One variant we discussed we wished there was is some means to shuffle/rearrange your cards. Once a juicy card like a 0 or 1 gets identified, it becomes a target for everyone, and might exchange hands repeatedly. I bought a deck of the game after playing it and will eventually experiment with house rules like discarding a 13 letting you randomly shuffle your cards or something.
Enjoyable, simple, casual. Unlikely to appeal to the wargamers or crunchier eurogamer set, but a fun little game for a small group of people, especially if no one wants to waste time explaining complex rules to the game. Add alcohol to make things a little more random as short term memory goes away.
My score for it: 7/10 - nice thing to toss into my bag when Fluxx is feeling overplayed.
I liked it enough to buy a deck for myself. Although a sharpie and a normal deck of playing cards could be used to make one just by adding the appropriate "Spy","Peek", and "Swap" instructions.