Muddled Mess
It seems like Brave and the Bold was a title that just existed to as a way to use D.C.'s incredibly popular Batman character to introduce readers to other titles. In this issue, clumsily force-fitted in between Swamp Thing #s 18 & 19, Swamp Thing is brought to Gotham as a carnival attraction, but helps Batman rescue the city.
There's a lot to hate about this issue - for both Batman and Swamp Thing fans. For Batman's part, he doesn't do any of the science or detective work (nameless minor characters do), nor does he do much of the action (Swamp Thing does). He does however get to fly around in the ridiculous 'Whirlybat'. For Swamp Thing's part, all he really does is what Batman tells him to do.
To make matters worse, the story has lots of leaps of logic - sometimes they catch them and try to cover them up (for example, Batman leaves Swamp Thing to do stuff then comes back later explaining that he "told Swamp thing to stay here" - apparently 'offscreen').
The whole thing comes off as hurried and 'we'll cover our mistakes with lines of dialog'-ish. At one point B.B. Riggs, the carny just shows up to help Swamp Thing despite having been hunting him a few panels earlier. It's just a quagmire of sloppy work.
Avoid.