So instead of watching IMAGINATION rainbow train this year I'm going to watch the new PreCure in its place. Do I need to be familiar with the past series to enjoy it?
Not at all.
Is this even good?
It's the anniversary series but so far all that can be considered a "throwback" are past characters thanking you for sticking with the series for 10 years just before the OP. You'll miss the joy and nostalgia from seeing them again but that's about it.