I know the Depends products are fairly basic, and nowhere near as good as quality diapers, but IMHO they are not terrible either, particularly for wearing just for fun.
I don't think I would trust them if I suffered from actual incontinence issues, and had real uncontrolled accidents, but for ABDL playtime they are quite sufficient. I've been buying them on and off for years, and have used the diaper style with the button up elastic side tabs, and found those a bit awkward to fit snugly enough, therefore more prone to leaks, but the fitted briefs aren't to bad at all.
When I wear the fitted briefs, I am usually playing in my little mindset, and I pretend I'm wearing a pull up. If I tuck myself so I'm pointing down, and make sure the briefs are pulled up properly with the leg guards fitting snugly, I can manage quite a good sized wetting, providing I don't just let go all at once and flood it completely.
Having said that, I know some people, me included, like to occasionally fully flood a nappy after holding in for a long time with a lot of build up. Even if you have a good seal, the capacity is nowhere near that of better nappies, and they will overflow quickly.
But realistically I think they get a bit of a bad rap sometimes. They are cheap, available everywhere, and if managed properly can withstand a fair bit of punishment.
But I have learned to make sure they are pulled up and snug. I wouldn't trust one worn under my clothes for any period of time to not leak after even a mild dribble. But as a playtime accessory they do a decent job.