Jake from Verbling here. Thanks for this feedback. Really appreciate it. Many users are reporting switching from other sites once they've gotten the first few phrases down and want to practice with real native speakers. Talking to real people seems to serve as an extra injection of motivation.

Re. abuse: Verblings make accounts and that carry a crowdsourced reputation. We can see how well-liked our users are based on how their conversation partners rate them. Users with serious abuse reports filed against them are investigated and, if substantiated, kicked out.