I'm not sure if all of the progression system is in. But once you have a pretty good collection of weapons and skills. Seasons after the first become pretty easy, especially if you are just a sword berserker--once you get the timing down.
I was thinking, maybe the vamps should get tougher sooner. or you should lose all equipment after a season. I do see more elites and higher goal counts. but with all the money and weapons it loses some of the challenge.
Edit// Ok, nevermind, after enough seasons you get a new "generation" and then it restarts the equipment. Cool.