A good idea, could be a lot better if it was an actual game with story and upgrades.
Honestly, the combat in the game is actually pretty fun but there are a few problems.
First, the combat is often unresponsive for the sword and board character. Supposedly, there are certain combos you can do (like X, X, X) but they only seem to work for certain classes. Sword and board can't do it, even though it says they can. Other classes can. It's kind of weird. Some of the controls are also responsive. Try to dodge and end up rolling nowhere and getting stabbed. Some of the fighting is just cheap as well, you'll make the right move then get smoked anyway.
Also, the online play is awful. I don't have the best connection, but this game is absolutely beyond laggy. It's horrible. I've literally pulled off full combos right on top of the other guy only to hit nothing, then find myself getting killed. Online fights are a crapshoot.
The game has no story (not really surprising), it's sort of like an old school Mortal Kombat game with gladiators - just fights and gear grinds. You don't actually have to pay to play, but your gear is pretty limited if you don't. All things considered the game isn't really that bad, but it would serve better as an idea block for a full game. Give it a story. Start as a gladiator, fight, earn your freedom, start your own school, win it all, something like that. Not a bad idea for a game, and let's be honest, it's free. For the price it's worth a download, just don't expect a AAA experience.
Edit: I wanted to add this after playing this game a bit longer. It is unfair. You'll constantly be matched up against AI with ratings that are double or more your own rating. Now when you're rating 40 going against a rating 80, that's not so bad. When you're 200 going against 400, that's a huge amount. Also, these are fights to the death, and often result in the loss of your fighter - and if you've picked up one of the coveted boss fighters and he dies, well you're screwed. These aren't boss fights either - where they tell you the ranking of the guy you're going against. They're random fights. I've seen people 100 levels below my guy, and guys 250 levels above my guy. It's completely ridiculous. It's like they just keep upping the difficulty on you until it's too much. And they don't do it in small steps. They do it hundreds of levels at a time. Coupled with that are unresponsive controls. This game often pits you against both your opponent AND the game, and for that I'm taking a full point off my review. A cheap game isn't much fun.
Oh, and if you suck with a particular play style, too bad. You're going to be forced to play it to advance in the game. If you're amazing at all but one of the weapon styles, you're going to have plenty of instances where you're stuck with the weapon style you hate and won't be able to advance without some real luck.