What I expected when I got the mod was the arena quest from Oblivion. I was wrong. It was so much more. First of all, all the fights don't take place in the same arena. You get to choose where you want to fight: Windhelm Arena, Ratways of Riften, Orcish Stronhold, Imperial Fort, or a smuggler ship. As you go up in rank you can challenge different champions. There's one for each arena, and with every victory against a champion you're rewarded with a unique weapon, which gets added to your trophy room in the Windhelm Arena.
The Windhelm Arena, the Ratways of Riften, the Orcish Stronghold, the Imperial Fort, the smuggler ship
The mod Pit Fighter also has a sort of DLC called Pit Fighter: Travels. This DLC-mod gives you the opportunity to compete in arenas around the continent: Summerset Isle, High Rock, Valenwood, and Morrowind. As in the previous mod, you can challenge random enemies or a champion and with each victory against a champion you're rewarded with a unique weapon.
The Summerset Isle arena, the High Rock arena, the Valenwood arena, the Morrowind arena
I think that I was over-leveled for this mod in general, but I still liked it, and at least the arenas in Summerset Isle and Valenwood offered some challenge (as in I couldn't one- or two-shot the enemies there). If you want to get the most out of this mod you should not be level 70+. Just saying. I was overleveled even for the unique and pretty weapons. Nothing can beat my character in full-on dragonscale armour and dragonbone weapons.
The trophy room really looked nice in the end, though :)