Ever since Star Wars: the Old Republic went Free-to-Play, it has contained an element of gambling. Cartel Packs, which cost real-world money, may or may not contain any items you actually want depending on a random number generator. And when the Dye Modules were added later on, it was another gamble - you could end up getting some dreadful color combo that makes your character look like a cheap knockoff action figure, which you can't even give away, or you could luck out and get Black/Black which is still worth 3 million credits.
Either way, it's always been a gamble. Basically, you have your choice between Craps and Roulette. You always get some kind of payout for your money, but the odds of getting anything good have always favored the House rather than the Player.
Game Update 2.8: Spoils of War adds slot machines into the mix. Actual slot machines. According to the SWTOR website:
Soovada ("Spoils of War" in Huttese) is an annual celebration of total extravagance in Hutt culture, originally celebrated in the summer season of Varl after successful military campaigns. Rival clans compete to prove their superior wealth, attempting to sponsor the most parties, pit fights, bounties, gambling, and every other public display of fortune and excess imaginable.
Popularized among outside cultures during visits to Nar Shaddaa, this exuberant holiday is now celebrated on hundreds of worlds across the galaxy, where it's simply known by its Huttese name; any connection to ancient wartime looting is largely ignored.
Head to the Star Cluster or Club Vertica Casino on Nar Shaddaa and you will find banks of new slot machines featuring two games: Smuggler's Luck and Kingpin's Bounty. The rules for both games are exactly the same: put in a token, push the button, see if the arrow lines up with the highlighted arc. If the arrow lands inside the highlighted arc, you win. If not, you lose. There's no way to engineer a win - the relative positions of the rotating arrow and arc at the moment the button is pressed have no bearing on the outcome. Your outcome is determined by a random number generator the instant you click the machine. Also, note that the position of the arc and arrow do not determine whether or not you win or lose - the win/lose mechanic determines the position of the arc and arrow, and just because it's pointing dead-center doesn't mean you should have won the jackpot.
When you win, you get your token back and can play again. Occasionally, you will win a little something extra. The "something extra" depends on the game you are playing; on Smuggler's Luck machines, you can win double coins, a "Feeling Lucky" buff or a Kingpin's Casino token. On Kingpin's Bounty machines, you can win Gold Certificates or, very rarely, one of the new mounts.
I have seen people claiming to score a "something extra" win about 1:7 times, but my own win:lose ratio was more like 1:15 or so. On Smuggler's Luck machines, I won more often than I lost, but eventually I ran out of tokens anyway. On Kingpin's Bounty machines, I lost often.
There's a bit of strategy involved here. Kingpin's Casino tokens are 50 times more expensive than Smuggler's Luck tokens, but the Kingpin's Bounty machines are the ones with the big payouts. So the trick is to play the cheaper SL machines until you get a) Kingpin's Casino tokens, and b) the 2-minute "Feeling Lucky" buff, which supposedly "greatly increases your chance" of winning at the Kingpin's Bounty machines.
In this case, it seems we may need to redefine a few English words. Your chances of winning stuff with the "Feeling Lucky" buff are:
I suppose they also count getting your token back as "winning," and to be fair, that is over 14% more likely with the buff than without. And you're around 16% less likely to lose your coin outright.
Your mileage, however, may vary - mine certainly did. My Juggernaut lost his hard-won Kingpin's Casino token on the first go 4 times in a row with the "Feeling Lucky" buff. I felt about as lucky as the Scorpio Killer felt at the end of Dirty Harry. Then my Operative went in, spent less than 10% of what the Juggernaut spent on tokens, and won two speeder jackpots. RNGs are a cruel mistress.
Don't do what I did my first time there. I bought hundreds of thousands of credits' worth of Kingpin's Casino tokens, at 50,000 credits each, and lost all of them almost immediately before I figured out the much more financially-viable strategy of playing the cheap machines to get the expensive machine tokens. 50,000 credits buys 50 Smuggler's Luck tokens, and you can turn that into a good fistful of Kingpin's Casino tokens, instead of getting just one by buying it directly. I spent and lost around 800,000 credits in a matter of minutes. It would have taken much, much longer to burn through that much money buying only the Smuggler's Luck tokens, and instead of ending up with only 6 Gold Certificates for all that money, I probably would have ended up with far more.
Obviously, the main prizes everyone wants are the new mounts: the slick retro-style Vectron Magnus speeders, which kinda look like scaled-down late-40's Chevy Coupes, or the Kingpin's Rancor, which kinda looks like a rancor, are the big-ticket items. Some folks have lucked out and won those almost right away, others have spent hundreds of thousands of credits and gotten only the Gold Certificates.
The Gold Certificate prizes are alright. The gear has a "classic mobster" vibe, with blaster rifles clearly modeled after the Thompson M1921 submachine gun (also known as the "Tommy Gun" or the "Chicago Typewriter"). The armor pieces are re-skinned high-level Smuggler gear.
This event is a fairly cut-and-dried credit sink. The House always wins in the end - even if you're one of the lucky few who wins the rancor mount right away, there are hundreds of other players plinking token after token into the machines and coming away with nothing. On the other hand, it's "honest" gambling - the Cartel Market, selling chances at phat loot for real-world cash, seems somehow more sleazy than straight-up video slot machines with a terrible payout chance. With a slot machine, there's no pretending you're not gambling, because it's a slot machine. With the Cartel Market, the gamble is buried beneath the marketing.
The casinos will remain operating into August, and the "Summer of SWTOR" will see the return of a number of other special events - Relics of the Gree and Bounty Contract week are announced, and I have my fingers crossed for another plague outbreak... which, admittedly, sounds pretty damned horrible outside of the context of the game. And be sure to check in during the first week of July - the entire week is a Double XP event.