Yeah, if you stick it on a Halfling and find Cydstepp, you can be a warlord on top of what you already are (and it's plenty silly in case you're a Rogue or a Sorcerer or Bloodmage or...). It's scummy as you can't prep Cydstepp, but so was the old Cydstep Rogue and it still didn't stop people from going nuts with it. Being a warlord while still being something else is kinda... busted. I'd say it makes any halfling into a ghetto warlord it it didn't in fact turn you into a... gangsta warlord, I suppose?
Otherwise it'd be good with thieves if it worked with them, and it's obviously good with Priests due to overheal. It's also probably good on Rogues, too, 50% overheal from potions negates their innate health deficiency as long as you can tactically burn potions (and if you're a Halfling, you can probably go nuts with those especially if fueling Trisword and/or alch scroll). Could be good with Transmuters for the same purpose, and it works with anyone using JJ strats I suppose. Also warlords, ofc, ghetto, gangsta or ones with a permit.
Anywho, last I heard, overheal = good. Lets you fight stuff above your level and stuff. If you're going full-stupid with stat pools, most single-issue debuffs are also pointless if you can potion spike stuff (and seeing that halflings can bloody well potion spike anything anyway in innumerable ways, having something which augments it is also fine I suppose). Berserkers are also a lot like priests in that they always take that little bit more heal/health for getting one more critical hit in, and love fighting stuff above their level, I bet there's a good cauldron Berserker build or two out there.
Also, words of wisdom for the uninitiated into one of the greatest secrets of Desktop Dungeons - if you cant figure an item/class/glyph/god/whatever out, keep throwing halflings at it until it breaks. Or at least until you end up discovering some unrelated bit of complete insanity.