i'm really not sure about whether or not it's a "good tama". i consider all the tamas good i think it's easy to figure whether or not your tamagotchi is a good character. it all has to do with how good you took care of it. normally if you let it lose two hearts or more in either categories, you'll get the lesser quality characters.
a little info about the little guy you have now. its name is kusatchi. its average weight is about 30 pounds (it's good to keep them around their average weight. it helps you to get a better character). it wakes up at 8am and goes to sleep at 10pm. its favorite food is melon, and least favorite is meat. this was all taken from www.tamagotchischool.com, which is a pretty cool site
hope i helped. if you have any more questions, you can post em here. i'm sure others and myself can help you out a little more if you need.