In my kit the stab-bottle was also just a bit more than half full, but all bottles was in a plastic bag, so i could see that there was no leakage, everything was dry. I think that it is supposed to be half full since the stab have so much more capacity. 100ml would be enough for 60 films.
I got developer, bleach and fix for about 20-25 films, and i got stab for about 30-35 films despite the bottle being a bit more than half full.
I developed with this for the first time and I am pleased with the results. Can't wait till I get in the groove of using. Definitely need to update my downstairs faucet.