Truly excellent. Extremely addictive, I've been playing it since yesterday.
I do have to agree with the majority of the reviews I read though. There is at least one bug as well as general game play flaws.
Bug- Certain points in the game you will be playing and an enemy will chase you, if you get to the edge of the area and the enemy runs off screen they will not come back. Once this happens if you weren't one enemy away from the end of the wave then you are stuck there and forced to quit. This gets especially frustrating when you are 3 waves away from the end with several thousand arrows and only needing 1 more point to upgrade your last bow and get that achievement. But I digress.
Gameplay- I really have no issues with the difficulty. It starts out easy enough and progresses slowly enough that you aren't being overwhelmed by wave 10. I might suggest a difficulty setting though for those people complaining that it was too easy/hard.
-As it was stated before, the money drops are basically useless as the price of health potions become so obscene toward the end that all the money you collect in one level basically goes to replenishing your health. The copper drops are adequate enough, but for almost 10 waves you are receiving the same amount of money even though the enemies are still getting progressively harder. Perhaps a set amount for each enemy would be better than a set amount per stack. Then you could base the stack designation (copper, silver, gold) based on the amounts.
-Along the same line is the weapon/arrow drops. The way it is set up in survival mode fits perfectly seeing as it is a survival mode. My only suggestion is that you add arrow drops in the campaign mode as well. Perhaps that might help off-set the low values of the money drops if you chose to leave those the same. As for the bow drops in the campaign mode, they are sometimes too few and far between. I personally went from wave 12-15 without receiving a single bow drop. Now, if you added arrow drops to the campaign mode you would not really need to adjust anything as that would help replenish your arrow count without depleting as much of your funds.
The last thing I will mention is perhaps more of a question than a statement. In the achievements section there are several achievements labled 'Unlocked Cheat 1-9'. Are there actually cheats that have been unlocked by gaining this achievement? or are they representative of something else?
That is all I will say. Despite the aforementioned issues I personally saw, this is still a very excellent game. I look forward to playing a second should you choose to make it.