Comments posted to our Dark Souls 3 Wiki
I've been using whips in my mainhand for a couple dozen matches or so now, and I must say they are pretty good.

Whips are a DEX weapon with quite the range but their normal attacks have the swing time of UGS, which is an awkward amount of time for a DEX weapon to perform a normal attack. That isn't to say it's useless. It's more or less like the Dark Sword's weird strong attack. It has its moments and times that it can be used. On the other hand, their strong attacks hit farther, strike a wider area and take less time to charge. Their rolling attacks have just the right amount of range to catch someone after you roll away with <70% weight. Their running/back step attacks are so-so damage-wise but have quite the range too. And their jump attacks have quite a fast leap and wide horizontal sweep as well. The cherry on top is their WA which is good for catching people who roll close or into you.

All those things considered, whips are no good to people who take normal attacks for granted, and in a game that has designed normal attacks to be the bread and butter, it's not unreasonable to get the opinion that whips are bad weapons. So if one know how to mix timings and switch up all the attacks a whip has to offer, whip users can go toe-to-toe with halberds, great hammers and UGSs.
I wish that whips were stronger, and more viable in combat
They're made to stun, not to kill someone
Whips are great for stunning someone long enough to wind up an ultra greatsword attack/hit a pyromancy
If you use whips in pvp you are a *****
They're whips, dude. Git gud or go home