Bigger Forest is a product in the Pathfinder Flip-Mats line that's almost half-again as big as traditional Pathfinder flip-mats. Each side of the one-inch gridded sheet has different terrain on it.
One side depicts a fifteen-foot wide stream meandering through a light forest scattered with large boulders. There's some cool features on this map, such as a single log serving as a bridge across the stream, a cave, a clearing featuring what looks like an ancient ceremonial site, and even a small waterfall. This scene offers numerous tactical opportunities and is beautifully illustrated.
The second side depicts a scene that's harder to make immediate sense of; I think it's supposed to be a rocky scrubland in the height of summer with barren trees scattered about a plateau. There are multiple cliff edges and a small pond. One part of the map has a scattering of stone slabs creating what (I think) is a cave underneath them and a trail that has some partially visible paving. Frankly I don't quite get what's going on in this scene. The back of the cover calls it a "blighted dead stretch of former woodlands."
The advantages of Bigger Forest is that it is indeed an impressive side for a flip-mat, and is quite easy to use since it allows for wet erase, dry erase, or even permanent markers. My criticism of the product, and it might seem an odd one, is that there's not actually that much forest! On one side, the stream, clearing, and rock outcroppings take up such much of the scene that the trees and undergrowth are pushed to the margins. Ironically, the more distinctive features there are on a flip-mat, the less likely I am to use it because I don't want subsequent encounters to seem repetitive ("wow, how many ceremonial sites are in this forest, anyway?"). On the other other side of the flip-mat, a blighted forest of dead trees isn't what I expected from the product title and is much less likely to see use in my games simply because there are fewer "blighted forests" detailed in the areas my PCs are likely to visit. The last suggestion I'll make is that since the inside front and back cover of the packaging are blank, they would have been the perfect place to give the GM some suggestions on how the terrain features operate: how tall are those rock slabs, are the trees of the type that provide full cover or can those squares be moved through and only give partial cover? Etc. A GM can research the terrain rules and make decisions, but a quick "cheat sheet" specific to the flip-mat would be quite handy.