Loud diesel, pine and earthy spice. The head effect lands fast and then settles.

What exactly is in it?

Not one fixed cross. Most versions pair GG4 with an OG Kush cut, usually SFV OG or Ghost OG, which makes this a cultivar family rather than a single plant. Two farms selling it can be selling different things.

Indica or sativa?

Hybrid, leaning heavy. Both sides of the usual cross are known for weight rather than brightness.