I love these dice. They're heavier than plastic, but lighter than other metal dice, which makes for a great roll. I've got several sets of metal dice, but my Gravity Dice are the only ones I use now. They roll randomly, as best I can tell (30 rolls per dice by hand, good variation of numbers). The colors are great! I have a mix of matte and shiny dice and while I love the look of the shiny coating, the matte ones are easier to read since the overhead lights don't glare on them.
My only beef with Gravity Dice is the price. Other metal sets cost anywhere from $20 to $40 and these are more than double that for a full set. I bought mine individually and came out cheaper than their full set, but I also had specific numbers of dice I wanted (3 d8, etc).
I would definitely buy more.