Fun but extremely slow.
Okay so sliding around as use of an attack is kind of an interesting concept and I have to say I've enjoyed it a lot. I also like revisiting the levels with different difficulties and I find the Gold and Platinum to be both difficult and thrilling.
But let's visit some issues now.
Speed. The game is already designed around an element of RPG style game play that I completely despise and that is grinding. Power Leveling all the characters is just a time consuming task and later on it is near impossible with how long it takes. With the slow pace of grinding there is also how long it takes for a dash move to settle. After you dash it takes time for the attack to decrease momentum and eventually you are watching your character taking seconds to just finally halt to a stop. It wasn't so bad at first but then later the repetitive nature of how long it took for a dash to finish built up into what essentially amounted in several hours of game play that could have been already sending me well on through the progression of leveling up and continuing to the next stage.
Now aside from this there were also some really irritating glitches and a terrible physics engine.
What seemed like logical ways to ricochet off of walls just didn't work and would often send me back in the original direction. Sometimes my tricks would work fine, but other times it would just fail and with the same surfaces and same angels as well. This shows there is a great deal of inconsistency when using the walls and thus makes them very unreliable. A really annoying glitch is that sometimes it would show the screen centered away from my character after an attack when it was still my turn, also the combat menu was often off the screen or somewhere ridiculous and unreadable.
Other factors to consider as well. You should slow down the text speed in combat so I can actually read what weapons an enemy is about to equip and also you should work on some of the glitching. Obviously you cared more about the general design to notice the functionality. Your menus and indicators that were suppose to help me were off base and instead became a hindrance.
I also wish I didn't have to unlock the other characters. Another issue is that all the knights are universal to so many degrees. I mean, quite honestly at some point increasing speed is just useless and so eventually Nana gets to be the high damager (and she's even the best at it) and gets out of combat quickly. You should maybe work on giving us different abilities differing with each knight. I know this game doesn't work and follow on magic and solely on Dash, but honestly there should be like buff abilities or something that actually fits the job description of some of the characters. Like make Nana have the ability to camouflage herself or the Barbarian to go into a fit of rage after a certain percent of health is gone, and even the Paladin to have taunts because he is the tank.
Also work on the A.I., they do really stupid stuff and half the time it seems their strategy is to either go for the weakest person or go for the closest.