Ok I don't think you are giving it a fair summary. Users who did not like it actually very objectively pointed out that the Act 2 rehashed a lot of the same sets and characters and did not introduce much new elements in the story - in other words, it felt rushed and empty following a promising Act 1. Which it probably was.
The positive critic reviews acknowledged these aspects of the game too, but still gave good reviews if not quite as glowing as Act 1. Eg "While I wish that Double Fine kept taking me to new and surprising settings, Act 2 makes the absolute most of each screen of its world. Itβs an adventure that I loved seeing through to the end. "
If you look at the comments on the metacritic "user reviews" page, there are a lot of people disappointed that the game wasn't sufficiently like the classic LucasArts point-n-click adventures.
You get the feeling that the most vocal users didn't review the game on its own merits. It ended up being very casual, which means the target audience isn't well represented by commenters on gaming web sites.