They're pretty good.
Used one of them for more than 2 days and got no ban.
Only thing is that, like Zezecha said, zeals per hour vary because it's not a paid bot so they might be some small problems.
the reason the zeal per hour differs is because you yourself don't have any relative effect on the outcome of the game. anything above 3.75 is good, above 4 is great.
I have experience with rsbots.net soulwars script and it was pretty good, so if you plan on doing a lot of zeals, i would highly recommend paying the $15