shookONES, DanyoWanyo, mrrobxc have summed Zebrina up pretty well. Just like shook said, their personalities differ from individual to individual but to echo everyone else; they're IME one of the most peaceful Creni's around.
Mine unlike shook's gets along fine with my African Scats all 7 of them, though like shook mine does take issue with my Ingots. They also hold their own fairly well. Mine used to scrap with an 8 inch Mammon female fairly often. The Zebrina never provoked but made her position in the pecking order understood. Biggest surprise was how well the Zebrina got along with my T1 Pike. The Zebrina asserted herself(I believe it's a female) over the T1 the first day. Since then they coexist with no aggression that I see(knock on wood) and spend much of their time cruising beside one another.
Outgoing, active, peaceful but can hold their own these beauties have a lot to offer. I had already been enamored by pikes but getting a Zebrina sealed the deal as far as making them one of my all time favorite species I've kept.