Prototype became repetitive too fast for me, and I thought the history was put together in a weird way.
I really liked all of it, story, gameplay and presentation combined. Spent ages completing the Web of Intrigue and found this really deep story, the gameplay itself is just incredibly fun and the presentation, graphics, density, sounds, etc, combined was just fantastic. It was a game that just "clicked" for me and when I finished it, I felt like I'd been on a great adventure, which is something I very rarely get from games, let alone open world games. I connected to all the characters, especially Alex, I adored the depth of the story and the universe it created, the gameplay was just tons of fun and deep enough to not get repetitive for me personally, and the presentation, although the graphics weren't the best, I thought was incredibly well done.
But to each his own.
Continuing on to Interstellar Marines, I get kind of the same feeling. The story seems so fantastically deep, the gameplay looks extremely deep and fun and the presentation, combined with the gameplay, looks so spot on, making for a very immersive experience. I never liked GRAW, but this looks to be one of my favourite games of all time, IF ZPS don't stray from the path and just keep focused on fulfilling their vision for the game and delivering an extremely fun and polished experience, then it is guaranteed to be one of my top ten games. The co-op experience makes it just that much more fun and the very fact that I'm financially involved in the making of the game just makes me even more excited for it. When it's finally released, and if it's great, then I will feel like I'd been on a very fun adventure.
Then I will wait another 10 years for the sequel. :p