Okay, so I finally got a chance to play with my Devilgotchi for a little while and I like it overall. To be honest though, I prefer Angels. At least now, anyway. Only time will tell. When I first started the Devil, I immediately was taken aback by the beeping. Not only was it different (which is good) but it was noticeably "louder" than (I mean this in respect to) the Angel. It's not the typical beeping you hear with regular vintage Tamagotchis. It's more of like a buzzing, for lack of better words. I got used to it after a while though.
Another thing that I find a little bothersome is the late-night antics of the Devil.
I like to keep the sound on all the time in general for Tamagotchis, but it works out for the other vintage Tamagotchis because they don't make sounds in the middle of the night. Well, the Devil does. There are certain activities that the Devil does at certain times, which is a pretty neat function but one can be particularly annoying: I think about every half hour or so after it goes to bed until midnight (but sometimes early in the morning), a bat from "Devil World" will fly up onto the screen for a few seconds and play a little tune, which can be a little startling at times. Lucky for me, I usually stay up past midnight anyway, but I would recommend turning the sound off, just through the night anyway. Otherwise, I think the events that happen are pretty cool and it varies based on the character you have or what time of day it is:
https://www.peppersoup.net/tamasquare/devilgotchi2.php.
Oh, and I was also disappointed (and probably also misinformed, by Wikipedia, uncharacteristically) that the Devilgotchi doesn't have a motion sensor. I was kind of looking forward to that, but it doesn't seem to have one. Unless someone can helpfully steer me in the right direction regarding this so-called motion/sound sensor. The Angelgotchi/Tamagotchi Angel, on the other hand, utilizes a motion sensor.
Now onto some of the things I like. One of the first things I noticed about the Devilgotchi is how incredibly low-maintenance it is. Even more so than the Angelgotchi/Tamagotchi Angel, who goes through the traditional baby stage that regular vintage Tamagotchis do. The Devil skips that altogether. I also like the fact that the Devil misbehaves (screen goes black while Devil appears white, Devil throws the pie back at you, pretends to sleep during the game, won't let you clean the screen, etc.). I know, it's kind of counter-intuitive, but the animations are pretty cute and it's fun trying to lower the Devil Power and all. The game is different: the Devil eats the stars rather than trying to jump over them, like the Angel does. Like the Angel, if you are successful on all tries in one game, 2 happiness hearts get filled up instead of 1. The handshake function is cute too: once in a while, the Devil will call for attention and will appear to be smiling on the screen. This means that he likes you and wants to shake your hand, which I think is pretty cute. It also helps lower the Devil Power. It's similar to the "praise" function on the Angels.
This is what I have so far. Maybe as time goes on, I'll find other neat things about the Devilgotchi. All things considered, it was worth the $70 I paid.