I've got a Polar Bear also, it's the smallest size. Similar size externally to the cheap soft coolers I had been using, but about half the space internally due to foam thickness. It works for me, but I usually put lunch stuff that doesn't need to be cold in my computer bag.
I also have a small Ice Mule cooler I bought for pack-in use. It's not a convenient shape for daily carry, but I'm impressed at how durable the materials are. It seems to keep cold better than my Polar Bear, but I've never compared side by side. It seals like a dry bag (and floats!), so no zipper to fail. If you want a soft-sided cooler but don't need carry handles, it's worth checking out.