I'm playing TF2 and CoD4 at the moment, but I plan on playing through Mass Effect and Assassins Creed next weekend.
Sure, after you complete it the first time in around 10 hours you won't go back straight away (although there are some extra modes if you wanna win some extras), unlike Ico, Colossus is the kind of game you'll come back to everyone once in a while and play through again. Maybe not tomo, or the day after but some day. Same with Psychonauts.In respect to Shadow of the Colossus. I spend almost 11 hours on my first try, and it's not adventure broken up by bosses. It's one boss after another broken up by platforming/exploration/action/puzzles. The ones that are more difficult, more puzzl-ish took me up to 80 minutes to finish them the first time. And at the most 20 minutes to travel to them if it was a confusing path.
You don't just run around looking for bosses, you are actually guided to them. You really should find a way to play it somehow, it's really non-classafiable. And if you do, don't follow a walkthrough. Figure them all out yourself.