I like it overall, because I just like this kind of game. The graphics are good, as is the reaction speed and enemy scaling. But it was a bit easy as the levels went by.
Perhaps it was because I chose assassin, but I soon noticed that, even if you chose to wait for perfects every time, it still is more powerful over time to just spam space at the speed that gives you 1 damage every time. Especially once speed got to be about 200, It began doing over 20 damage per second (limited, in fact, by my ability to spam space fast enough). Some of the weaker monsters would actually take as much as 8 damage at this spamming speed. On the other hand, even with attack around 130, most enemies would only take 3-4 damage if I waited until the perfect time. Perhaps if the timer was weighted better, this wouldn't happen, but I believe that it takes away from the overall funness of the game.
Also, even when you were killed, you only had to pay 2000 gold to buy another life. Around level 300 or so, you would get at least 2000 per level-up, making it almost impossible to lose unless you get bored or decide to merely power up instead. Not to mention the fact that once you are killed, you get 5 skill points, and then fight only 1 more battle before leveling up again. This makes it almost more cost-efficient to die every time you get over 2000 gold, in order to quickly "gain" two more levels.
Finally, the way the bonus worked was a bit of a over power. Once an attribute is at 100, every potion becomes like a level-up, giving you 5 extra points in that area. With only 6000 gold, I can double my speed from 100 to 200. Basically, the game would become more challenging if, with every level-up (or even with every purchase of them), the potions became more expensive, making the player strategise in their potion buying.