Pretty good
I like this, it is quick paced, battles don't last forever. The secret to winning is to pick your battles. Don't fight harder enemies if you can avoid it, unless there is a chest or a or gem (not just money) behind them. A rule of thumb is, if you take 1 point of damage, it's like losing 3 gold (based on the cost of heal potions). It's actually even more than that because towards the end game you start buying up all the health and mana in the shop and have wasted money left over.
At the end of each set of levels buy up all the healing and mana you can, mostly ignore the other things because you'll usually find as-good or better in the dungeon.
I had to use the wings twice in the early part of the game (both times on levels 20-29) and then was able to go the rest of the game without using the wings.
On the other hand:
1. Magic is pretty much useless, except for healing. It takes too long to cast, battles are over in like 1 second anyway, and it's more cost effective use mana to heal than to deal damage. Plus you have to drag it onto the character which is annoying - you need a hotkey system. It would be good if magic had range so you could kill enemies without risking injury to yourself, and if it did more damage.
2. Final boss was too easy, when i fought him I had 9 large heal potions + a lot of mana potions for healing, and I didn't even need to use any of it during the actual fight. I just healed before fighting, then attacked the final boss with full health, and won in 5 seconds.
3. The game system with the elements and element defense isn't really explained well. It's hard to decide whether I should use an armor with better pure defense or with better element defense. Also, I only ever got the earth and water eyes for the entire game so for a lot of enemies it was total guessing.
4. The final reward (a sword) is lackluster, especially since you lose all your non-artifact items. If you go back to try out the new sword you find out you are actually weaker than you were before because you don't have the other items.