"The characters are largely annoying and the writing and delivery is almost universally bad."
I actually love the characters. As for the writing, I think it's intentionally cheesy, which makes it funny -- everybody in Britain groans at a pun, but we still love them.
If this reviewer gave it an 8, with the above being the only 'negatives', I think most Banjo fans would rate the game even higher.
Edit: Seems a lot of reviews want actual voice acting. I am so torn on this, myself. I love the throwback and I just cannot imagine the characters with voices -- it would be like giving Banjo a voice, which is super weird. However, if they want younger children to be interested, voice acting would definitely be a selling point... and let's face it, children are probably the primary audience besides nostalgic adults (who are looking back to a time they were children themselves).