The clicker itself is fine. There are goals (to earn all medals), the click differences between them are well-designed. The next step always feels “achievable” and “close” so you never feel like now is a good time to close the game because going further is not worth the effort. The final threshold isn't too bad (it's not some insane stretch that would take hours, or force you to get an autoclicker).
There is visual feedback to clicking and even on hover, so it feels fun.
I do have issues with the upgrades.
First of all, balancing. You have three available upgrades
– the first one gives you +1 for 100 (+5 for 500)
– the second one gives +2 for 250 (+4 for 500 (!))
– the third one gives +5 for 500 (+5 for 500)
Usually, the idea is to give more click power for costlier upgrades, so you get more value for powering through with less power and saving up.
Here, there's no reason to wait for +5 (it saves you four clicks over clicking +1 five times), and you actively get less for +2.
I'd expect something more in the range of: 100 → +1, 250 → +3, 500 → +7, so it's always advantageous to save up.
Then you can't actually purchase the upgrade when you have “100”; you have to have at least 101 to confirm.
But the bug with not unlocking medals sucks, and I imagine will be what will annoy most people, as you will achieve the goals, but don't get the reward.
I was unable to unlock 2500, so I restarted and bought only under ten upgrades and pushed through to 2500 and much further beyond, only to not unlock anything again. So what actually does “excessive clicks” mean? Surely it can't mean ten upgrades is too much.
Well, I reset the 250 medal a few times to figure it out. You have to hit the number exactly.
I purchased +1 at 101 and nothing else, and therefore eventually went 249 → 251. But when I did the same at +2, I went 248 → 250 → 252 and the medal unlocked.
If I'm right about this, then a significant amount of people (pretty much everyone who doesn't follow rounded values with multiples of ten) will eventually miss a medal.
I don't know how the conditions for unlocking a medal are implemented, but since you know all values (clicks, click power and medal threshold), you should be able to check for the exact click that will unlock a medal even if you don't hit the exact threshold.
This is the most annoying problem I had with the game, but otherwise as I said, everything else is really fine and it's a good clicker.