I have the feeling that the deal is quite interesting if you just play one every 12 hrs and if you wait until the jackpot is at least 100k - 150k.
The main reason to play it, is to take a part of the jackpot, not to win money or starcoins with a good hand.
So far I have played 13 times (with intervals of 12 hrs) and have gotten a part of the jackpot 3 times. Once 1.84, once 2.77 and once 2.13.
Total balance after all of this is 6.23$ positive.
On top of this, there is always a very small chance you hit the jackpot yourself (although astronomically small).
Second best would be to buy tickets. It costs you basically the same as just entering with money, but it's a nice way to make use of the starcoins.
I would not change it for money, because you'll have to pay rake over that (you'll get less money for the same amount of starcoins than the value of the ticket bought with the same amount of starcoins).
If you're planning to still play MTTs or STTs or
spin and go games, you'll get more value out of you starcoins by using them for this, than first changing it for money and then later using money to enter in those games.