One of the underlying assumptions I have about game reviews, is that the reviewer finished the game to completion(With the case of online multiplayer, MMO's, play through the game modes as much as possible). Is that too much to ask? Should all game reviewers just stop playing the moment they feel bored, write what they have, and call it a review?
Alright, let me ask you a simple question: for the purposes of this discussion, I'm gong to assume that since you brought this up and are complaining about it that you have played Muramasa all the way through with both characters. Otherwise, you'd just sound silly. Now, looking at this review what have you seen in that post-3.5 hour playtime that would significantly change a person's impression of the game if they disliked what they had already played? What game-changing addition suddenly makes the game worthwhile if you find it monotonous already?
I can tell you this: I have played through the game and beaten it with both characters, and the experience in hour 8 is the same damn experience in hour 1. The only difference is the size of the special attacks, the damage they do, and the damage the enemies can do and receive. Otherwise, it's the same damn game recycling the same damn dozen backgrounds over and over again. Based on that, I say the critic was right to stop when he did before the monotony unduly influenced him to score the game even lower. Now, if the game evolved or became deeper in some manner, I could agree with you. But it doesn't. What you see is what you get.
If a person doesn't play it all the way through, how can he rate the rest of this game? By word of mouth from other people who have? Maybe the game is the same all the way through, I don't know. But even still, his job is to review the game, not to give it a shot for awhile and render a verdict.
Let's look at it this way. I've never seen the movie Apocalypse Now. Oh, I know what it is about and am familiar with the story and characters and actors in it. I've seen clips of the movie on various shows and read reviews on it before. I guess I should write a review on it. I'm clearly qualifed since appearantly it is ok to go by word of mouth when reviewing something. Tell you what. Just to be safe, I'll watch the first 20 minutes. I'm sure the experience of the first 20 minutes will be the same all the way through the whole film.
Compare this to an actual movie critic like Roger Ebert. There have been movies he absolutely hated. Heck, he published a couple books on reviews of movies he hated. And even though he didn't like the movie, he watched the whole thing. There are some movies he was hoping would just end, that sickened him. But he did his job and stuck it through. That is why, agree or disagree with his opinion, when he gives a review, it has more weight to it than someone who watched the first half hour. Really, what kind of credibility can one hope to establish by offering a review on the whole product when only sampling a part of it?
And why would you argue in favor of such sample reviewing?