Pointless Celebrities is the prime-time Saturday spin-off of Pointless. However, just like most celebrity editions of shows, it pails in comparison.
Surely enough, it's the same game show, but with celebrity contestants playing for charity and occasionally some filler. The questions are pretty much the same as the original, so they aren't as dumbed down as on other celebrity versions of game shows (eg, Mastermind).
And of course, Alexander and Richard make for a great comedy duo, especially with the celebrities around. There are familiar faces, and there are faces you've never heard of before.
In the end, it's what it is, but seeing regular members of the public playing is better, in any game show that is.