I had everything but 3 of the games already, so I bought the last three by themselves.
Aside from the TF2 Potato hat + extra Portal pin (why the hell did they give out two of the things?), it really isn't that great a package of games.
Want a breakdown? Here are my thoughts in a couple lines per game:
* Aaaaaa is fun though a bit strange, however it doesn't really hold my attention for long.
* KickIt is just Aaaa played to your own music. It has an annoying addition in that now you have to rotate yourself to get points from scoring plates.
* Amnesia is decent and scary, but the graphics won't impress you.
* AudioSurf is worth having, but odds are you already do from one of its many sales.
* BIT.TRIP BEAT (aka, Pong on drugs) is ok, though it will likely annoy you. I feel no need to play it again after getting my potatoes.
* Cogs is like a Rubik's Cube with a stopwatch that also counts your moves. It's ok for some of the easier puzzles, but quickly they become so annoying that you just give up trying to get "Gold" times or give up on the game completely.
* Defense Grid: It's been ages since I've played it, but its a fun game and worth getting.
* Killing Floor is one of my favorite games, so much so that I even run a server for it for my clan. It's definitely one of the better games in the pack.
* Rush is interesting, if you've ever played Star Wars: Pit Droids, Rush is exactly that, except with cubes.
* Super Meat Boy is strangely fun after you get used to dieing 50000 times per level.
* The Ball I've only spent a few minutes in, but it's something like Portal, made harder, and plus a giant ball. (a First-person puzzle game).
* The Wonderful End of the World is... strange. Not much more I can say about it. You run around absorbing things (kind of like The Maw) and grow in size. Your goal: to absorb everything in the level before the timer runs out.
* Toki Tori is alright if you aren't bothered by the 'child-friendly' art style.
Overall from the whole pack I'd say Killing Floor, The Ball, and Super Meat Boy are the best. The rest are good too, but it really depends your own personal preferences. (And how much you like indie puzzle games).