The main use case is small payments. You open a channel locking X amount of funds, and then can send or receive small payments to/from other parties on the net

The main use case is small payments. You open a channel locking X amount of funds, and then can send or receive small payments to/from other parties on the network without broadcasting those transactions to the blockchain or paying fees. The only thing that is required is a route connecting payment channels from sender to recipient. For example, if A has a channel with B, B has one with C, and C with D, then A can transact with B, C or D.