I've only seen the 1st one. Nothing great, but it wasn't as bad as I'd expected, tbh. Strangely enough, I just saw some random movie on USA the other day that starred Missy Peregrym and Jeff Bridges called Stick It, which turned out to be written/directed by Jessica Bendinger (who wrote Bring It On), and I had the exact same reaction - "Eh, that wasn't terrible, I guess."
It was basically Bendinger's take on the world of gymnastics instead of cheerleading (I used to do gymnastics, love Bridges and enjoy Peregrym, so the curiosity was too much), but I feel like it was still part of the Bring It On franchise, lol.