I've never played either game so I don't know what all the fuss is about wither... all I know is that the cake is a lie.
All I know is that joke should've died a long time ago, even the guy who wrote it says he hates it now, well done everyone...
Anyway, Portal is great because it's different. It's an FPS where you don't shoot people, you make quantum space-holes to move around in way that would make your brain melt if you tried to think to hard about how it works. It's a very fresh twist on the whole genre, not to mention that the portal mechanic was incredible when it came out. On top of that, the game was hilarious, always a nice bonus. And Portal 2 is more of the same plus new fun stuff as well.
In short, the games are amazing to me, easily among the best ever made and I don't say that lightly. To top it off it's also among the funniest, if not the funniest game I've ever seen.
I can see how it's not for everyone, but I love both Portal games.