Despite some bad experiences with some users, I think the odds have been much more favourable in general this time than in some earlier promos(?)
There is no way of knowing the odds in the past or now.
My guess is the odds are different based on your collection; the more cards you have the less likely you are to get a card but instead a star, joker, etc but that is just a theory. Also what would be considered winning would be determined by what you hope to gain; the only win for me would be a joker card. A random card would be at best a loss or worse a double loss; 1st losing the credits and then having a card put into my collection I don't want.
I haven't purchased and cards in about a month and had over 500 credits sitting around from last year so in a moment of boredom I went ahead and tried the slots and then scratch cards. I figured I'd spend 10% of my credits and then just make sure any cards I buy in the near future are discounted at least 10%. I decided to go with the slots because I knew I could ignore the discount offers and no unwanted cards would end up in my collection. It took me about 10 minutes to spend 58 credits + the 4 credits I won along the way. After playing I realized I never had a chance as I think only the scratch off game offers the joker card. Until now I had only played the the slots once or maybe twice and but I figured I had already thrown away 58 credits so what difference was 10 more so I purchased a scratch off. It took me a bit to figure out how to work it and while figuring it out I remembered that this game would inject cards into my collection. Fortunately I got the 2nd best result and got the 10 credits back.
I stopped there feeling fortunate as I expected to lose all the credits I played with nothing to show for it. And while I did lose 58 credits and have nothing to show for it the only part of of it that I regret is loosing a little of my self respect and contributing to the revenue these games generate.
As far as all the winners ....
We have video poker, casinos, and horse racing in my city and I know more that a few that participate often in one or more of these. They always seem to remember when they win but never seem to remember how often and how much they have lost. I have nothing against gambling but I prefer my odds in the stock market and I have a small position in a casino because the way I see it the house always wins and anyone who tells you otherwise is at the very least lying to themselves.