How do you like that Ryobi circ saw? I still prefer my corded but the FIL might be making me buy him one.
The circular saw (CS) and sawzall both eat batteries (lithium) pretty quick but they get the small jobs done fairly well. The CS does a fairly good job for cutting small amounts of 1X and 2X material. If you need to cut a bunch set up the miter saw.
If you need to cut plywood (1/2" or better) have spare batteries around. You'll get two or three 8' cuts from a battery so for small jobs it does a good enough job. If you are going to frame a house go buy a CS with a cord.
The other day I needed to cut some corrugated steel. It was real light gauge and I had the CS handy. It was noisy and a little bit messy but it did the job. I was surprised.
BTW: I never had a battery powered CS before the lithium batteries came out. After using the CS with the lithium battery I tried to use it with the Ni
Cads.... That was a fail.
All in all... if you're not in a hurry and have plenty of batteries around the CS is okay. Just don't expect it to work hard all day on one battery.