We've investigated this before, and it depends. For just points for transactions on your card - barely to not really worth it if you are paying a credit card fee on the transaction for typical rates of points per dollar spent, and definitely not worth it if it means you are paying interest on your credit card transaction, which you wouldn't have paid if you used a debit card or cash.
Sometimes the credit card companies have promotions where they pay 1 (or more) point per dollar spent, and then the points are worthwhile as long as the transaction fee is at the low end of the range charged.
However, all the above depends on how much you spend annually on the credit card- if you don't spend much, then the annual fee is going to wipe out any benefit- you have to spend a lot - tens of thousands per year to cover the fees.
Some supermarkets (and maybe other stores) also give you points for money spent, and that can make it more worthwhile, but the cost is that you are giving them details of all your buying habits... which we were not particularly happy with, and so cancelled our rewards cards quite a while ago, so don't get those points.