Is concrete around a pool very slippery?

This really depends on what style of concrete you choose.  If you go with a broom finish look (plain concrete), this tends to be nice around a pool because it does not have to be sealed, and therefore keeps a sort of rough texture that does not become slippery when wet.  If you decided to go with a stamped concrete look which should be sealed, then yes, this tends to be more slippery than a plain concrete finish.  Our company adds in a special “grit” in our sealing material which gives the concrete more of a texture rather than being slippery.  We find this really helps especially when the concrete gets wet.  Always proceed with caution around a pool regardless of the material!