I wouldn't recommend a cordless circ saw in general. If you already have it fine, if not I don't think it's a worthwhile purchase. My cordless circ saw is worth having blades for. I have actually used it here and there but it wasn't that I desperately need that particular tool.
If it came in a kit you were going to buy anyway, I'd recommend you do the same. You'll find a use for it in some tight space.
OP wasn't asking about a cordless recip. Since it was brought up, I'll mention that my 18v recip is great, but again I don't think it's a replacement for a corded one, especially if you have one of the more powerful ones you will probably be disappointed with how long and how much effort it takes.
Personally if I were doing it for money the Milwaukee 15 amp is the one I'd choose, and if I really needed to get into some weird space that the compact could get, look at the corded
Porter Cable that bends and twists into all weird angles. I haven't seen that compact DeWalt in use to compare but I can tell you there's a whole lot of demo you can do with that PC one.