I played the demo and wasn't impressed... but then I gave the game a chance, and you should too!
I used to own a game store and I had/have the opportunity to play so many games that it's a bit telling to say that I don't normally "beat" or "finish" games like I use to in the 8 & 16 bit eras when I had to spend chore money on each game. There is just so much content these days, that it is easy to move on to the next game even if you currently like the one you are playing. That being said when I turned on this game I didn't stop for two days, except to eat and sleep, until I had finished it.
This game has some of the most memorable and scenematic things I have ever seen in a game and I think it's probably the best game I have played in years (not counting God of War, interestingly another PS2 exclusive)
The controls on the horse and even some climbing have been duly noted as a bit frustrating and nowhere will that be more evident than the final Colossus battle, but it's not enough to make you walk away.
This game is being touted as one of the finest graphical games on the PS2 though, and this is where I have to disagree... it's not all that pretty except at scenery in the distance, although the Colossuses are great looking on the aging PS2.
Enough of what you already have undoubtly heard from scores of others except if you own a PS2 and don't give this game a chance, you are really cheating yourself out of a lifetime of memories.
One last thing... WTF on that ending though.... ???