You know, that's kinda a difficult question.
I've always been a fan of Quantic Dreams games, and of course when Heavy Rain was announced, I was already hyped. I was saddened a bit because it went Ps3 exclusive (Being Fahrenheit completely multiplatform), but I still had my hopes high. After several years when it released I could finally play it thank to a friend who lend me his Ps3 (Though I already had "played" it via Youtube). It was an amazing experience, and it reminded me a lot, A LOT, of Fahrenheit in several aspects. Honestly, Norman Jayden had become one of my favourite gaming heroes (Thanks to his unshakable charisma, and his overall bad luck in life).
Now, I could finally play TWD thanks to some good deals during Christmas in Xbox Live (First chapter free, the rest of the chapters were 50%). Well, I was impressed, mainly because I normally think games based on something tend to suck. (Movie games are pretty horrible overall, I didn't know what to think about this one). It played well, it never glitched on me (Which is strange, because I'm a pro Glitcher), the story was great, characters were outstanding, and overall it made me feel bad. One of the few games that had me crying, I can say that to you. Not even Heavy Rain did it, I saw most of its twist coming (Except the damn Origami Killer! That was pretty clever.), but both games awesome.
Problem comes when you replay them.
They are both established in ficticional choices. The worst offender here is Heavy Rain (But mainly because it's longer than TWD). There are tons of things that would happen no matter what you do, even if they lack sense completely. Not cutting your finger with Ethan? No problem: he will lose it later, oddly, when a policeman shoot his finger off. You don't want to do the Bear trial? (The one that gets Ethan killed at the end of the game). Well, you're screwed: he'll do it anyway. You want Shelby dead? Too bad, he's inmortal - until The Warehouse, that's it. -
In the case of TWD, you are on an already established path. What you say defines you as a person, and what you do is a manifestation of it: but you'll pretty much end up doing the same things in order for the story to play itself. I can say, at least, that The Walking Dead plot has it share of flaws, but Heavy Rain left some heavy plot-holes for the sake of the story itself. There's one character that keeps bugging me out, whose line of action is always contradictory (Yup, I'm talking about you, Shelby.).
On the graphical side, I like the artistic route of The Walking Dead, but I have to admit Heavy Rain's were really beautiful. I ended up liking them more.
Overall I can say they are both great "games". I consider them games, I could understand people saying they're not. I'm going with Heavy Rain here, mainly because it has more replay value. But be careful, it is also disappointing sometimes when you replay it twice or three times, because then you see the power of illusion some games can create.
