Very small dent in the extension. Does not affect the paint. 
I'd describe the color as very dark grey. Not at all brown. 
There is a lip around the edge, so the table is not completely flush. Not a big deal, but may make a tablecloth look funny. 
Easy to put together... arrived with a tool, but I used a socket wrench.
Had to tighten the allen screws that were pre-assembled. One of 16 was stripped, but seems like it's redundant. 
Had to realign the lock tabs with a Philipshead screwdriver.
All said, took about 15 minutes including unboxing.