Generally, she's right. Well, not that they're too slow, but that they have a lot of tweaking and fidgeting that has to be done from time to time. They're not continuous action, like side-scrolling brawlers of old.
Metronomicon is a rhythm game with both RPG and old-school brawler in its DNA. Yes, you can upgrade your equipment and you can fidget with your attacks and, yes, you get more powerful as you progress, but when you're in a level, it's continuous action. So much so, in fact, that it can be difficult to keep track of your health or sneak a peek at your current enemy's stats to select the best type of attack, as you'll be too busy watching the directions coming down the track.
You control a party of four adventurers trained in the rhythmic arts, as they seek to learn about, and ultimately, defeat the strange monstrous creatures invading their lands and the strange music they bring with them. Initially, this is four recently-graduated students, out on their first foray into do-gooding. As you progress, however, you will discover other characters who will join your party, each with their own skills and quirks. You will always have four characters in your party, but you can switch them out to suit your playstyle and current quest requirements.
The music you'll dance/fight to is a nice variety of techno-alternative, including music by Jimmy Urine (from Mindless Self Indulgence), Shiny Toy Guns, Yacht, Perturbation and others. It's actually quite catchy and, on occasion, horribly appropriate. To wit, there's the song for the end boss in the Haunted Kingdom level, Fighting with the Melody (Jimmy Urine) with a bridge that says, "You are soooo dead..." So, so fitting.