Ok, I've tried them out! I'll narrate how it went, in more detail than is probably necessary.
Tl;dr at bottom.
I tried my blue one first. Pulled out the tab, and it was wonky right from the start: The screen would flicker in and out, and simply setting it down would cause it to reset. The buttons were responsive, though, and the lid on top sat back at a nice angle, so it was easy to see the screen. I chose a new pet to adopt multiple times (with it constantly self-resetting) until the screen completely died, accompanied by a stuttering hissing sound, like it was dying and begging for an end to its sad existence. I took out its batteries and put in brand-new ones, and it was exactly the same..except at the end, it made a high-pitch keening noise instead. Took the batteries out and put this one away. Definitely DOA.
I pulled out the tab on my pink one, and this one works much better...kind of. The screen is normal and it has yet to self-reset once, but the buttons are unresponsive and the lid doesn't sit back as far as the blue one, making the screen a little more difficult to see. I also noticed that the two center buttons were attached. Whenever I clicked one, the other would also depress (not enough to register as a command, but you could physically see it). A couple minutes of playing and whatever was connecting them on the inside snapped. The buttons no longer move together, but they now make a sticking sound when clicked and are even more unresponsive.
Scrolling through the characters, they are actually different from my four-button clear Tamagotchi fake (for reference, it's like this one
here). My clear fake had maybe about 30 different characters, all animals (and there were repeats, making the total closer to the 49 advertised). This one has animals as well, along with Spongebob characters, people, and Tamagotchi characters. I've heard of lots of fakes having characters like these before. As a side note, the character you choose is the one you get right away, so there doesn't appear to be any growth.
I can't compare the gameplay to the clear fake, because that was horribly buggy (my character on that one refused to do anything other than eat sweets; I couldn't feed it actual food, play games, etc.). This one actually works, in that all the functions behave normally. There are two games, a spaceship one where you avoid asteroids, and one where you play as some kind of animal and have to hit a frisbee as it comes near you. Both award gold, which you can apparently use at the shop...I haven't been able to use the shop yet, since I don't think I have enough gold.
There is a Chest icon, which has two options. One shows a star with a number by it...mine says zero. Almost seems like achievement points, if I had to guess. The second option is a letter. When I try clicking on this, my character shakes it head. I'm not sure if you might actually be able to receive letters, or if this is leftover from actual Tamagotchi programming and isn't used.
The sound is terrible and makes me want to claw my ears off; it switches between very low and quiet to shrieky and screechy without warning. Unsurprisingly, there's no way to turn off the sound from what I've seen.
Tl;dr: Downright terrible quality control, but there is an interesting variety of characters, and the programming itself seems like it could be fun...if it works. I'll keep playing around with it and see what happens.