Not much to look at
Definition 1 of 1
Pro Tip 1/3Understated Value
The phrase often hints that there's more than meets the eye, focusing on non-visual qualities. 
His workshop is not much to look at, but the craftsmanship that comes out of there is amazing.
Pro Tip 2/3Colloquial Use
It's commonly used in casual conversation, rather than formal writing or speeches. 
Sure, my bike's not much to look at, but it gets me around just fine.
Pro Tip 3/3Conversational Context
The phrase is often used to downplay expectations before revealing positive aspects. 
The restaurant isn't much to look at, but wait until you try the food!