I had a hamster before ^^ I know what you mean about not having time to care for them. Small animals like hammies and gerbies need a lot of attention. But, anyway, as to what gerbils are like........ Their really outgoing animals. Mine are not at all afraid of people and whenever they see me coming they will beg for treats and playtime. They crawl right into my hands and will snuggle up with me for a while before running off to play. I've never been bit by a gerbil except for Jerry biting me a couple times when I first got him. He was a little meanie xD Another nice thing about gerbils is their individual personalities. Hans is faster, quicker, and more active that Jerry. He's also an amazing escape artist. It'd be pointless to try and count all the times he's escaped. Jerry's fatter, and eats way more than Hans. He's also much cuddlier . And Jerry is WAY more intelligent than Hans. He figures things out quicker, and I actually trained him to tap a miniature ladder on command using clicker training. Hans never figured it out.
I also know Syrian hamsters are nocturnal, and dwarves are crepuscular (I think?) Gerbils aren't either, and they also aren't diurnal. They are awake any time of the day and night and take short naps throughout the day and night.
Also, even though gerbils are a lot of fun, I have to say they are definitely more work than hamsters, even though their tanks don't need to be cleaned as often. They demand plenty of out-of-cage time. They get bored and depressed if their humans don't play with them enough. And, unlike Syrian hamsters, gerbils are VERY social. They absolutely must be kept in pairs. And, even though it's rare, gerbils can declan or fight with each other. Mine did, unfortunately. Although that is extremely rare and it isn't nearly as like for a gerbil pair to fight as it is for, say, a pair of dwarf hamsters.