I kinda get what you're saying but I would have thought the answer was obvious in this case given the way that the series is being released and the fact that all of our reviews have mandatory scores.
If the question is why score, then I agree. But we have to keep putting them on to service those who prefer not to read.
And if you're really comparing to a novel (why?) then sure, you can have a 'so far so good' review based on the first couple of chapters, that's actually what some publishers initially judge books on.
Short of going into the future (which, I'm sure, would be apt for this series) this is the best kind of review you're going to get at the moment, and surely it's better to have Tom's eloquent gut assessment now rather than wait a few months to see where it all lands, by which point everybody will have seen it anyway.
Well, apart from me because I read the review and now I'm waiting to binge it.