My experience was:
I sold the first diamond at the first store, started digging, and midway through all the digging I found out that I could upgrade the stats. Then I thought "what keeps me from upgrading this like crazy?" and boosted all the stats.
I was cooking so much with that pickaxe.
Then I got to the second store, and realized "shit" upgrading that badboy so much got me in so much debt I couldn't pay with the loot I gathered, and had to give up and try again.
I REALLY LIKED THAT ! It made me realize on my own how the game worked, and the gameplay loop.
I don't have any complaints, besides maybe wanting some obstacules to avoid while digging (Maybe there are some down the line, I didn't got so far)
In general a very nice and well thought experience.