The pirate chest really sucks. If you're going to gamble 100 gems, I'd much rather roll the Deep Sea chest, it costs the same and it guarantees a tier 2 skin or better (so you're at least getting more than your 100 gems' worth).
Yeah thats the chest I rolled on sorry. I gambled 100 gems x 3 and felt ganked.
Now I realize why they have all the crappy skins you pay favor for. It's so when we burn gems on these chest they can do a roll and gift us the cheap skin.
Sorry I'm just not used to this (so I might be harsh). In League of Legends you can gamble on chests too- but you are for sure going to get a skin that costs 'money'. They have no equivalent to the palette swaps that this game charges gems/favor for. (Okay so LoL does have Chromas but they can only be bought with money and are -NOT- included in a chest roll)
tl;dr - I think the chests suck and are a ripoff

(Note this all just my personal opinion of course; other buyers might be way more lucky then me!!!)