The wagering requirements for this bonus can be extremely low if you choose to play slots with a very low RTP. For example, Playtech's Age of the Gods - Fate Sisters equals out at just 20x the bonus, which is very low in 2018. Of course the scandalously low RTP of just 93% means you'll likely go broke long before you have cycled your money through 20x, but it's nice of the casino to recognise the wide range of return percentages offered by todays video slots.
The downside of this of course is that the entire system used to calculate your wagering requirement is extremely complex, infact I'd say it has to be pretty much the most opaque bonus deal available anywhere and seemingly designed specifically to confuse those new to online gaming. The problem is further exacerbated by the fact that, regardless of which country you reside in, both your main balance and the bonus are both counted in dollars rather than our local currency.
Most sites give you a specific wagering requirement, say 30x your bonus balance, whereas Stars simply tell you that you need to earn four redemption points for each dollar of bonus awarded. The trouble is every single game has a different contribution to earning these points, even slots. On the one hand it is nice that you can play any type of game to earn these points including Blackjack, Roulette and Video Poker. On the other hand you'll need to check the game lists carefully to know how much you need to wager to convert the bonus to cash. If you want to play a whole bunch of different games with your bonus you may as well forget trying to work it out in advance and just check your account page now and again to see how many points you have earned.
Whilst the example of Fate Sisters I gave above equals a very low wagering requirement of 20x, other games such as NetEnt's Dead or Alive need twice as many bets to convert your funds to cash, whilst some games go as high as 80x or higher and some blackjack variants get as high as 150x!
As a result of all this complexity I'd consider what you intend to play carefully before opting to take this bonus. It seemed like a good deal with the games I like to play, and I did manage a fairly decent withdrawal out of it. Your mileage may vary though, and the 10 spins they throw in on top aren't anywhere near enough to factor into the decision either.