The term of the loan is variable, and depends on daily sales, but assuming you have a high volume of sales and take out a small loan, the effective APR is going to be through the roof!
For instance, suppose I take out a $25K loan with a $2.5K fixed fee. Now 15% of my sales go toward repayment. Let's say I pull in a little over $30K in sales a month. The loan will be repaid in about six months, and my effective APR is 20%! Might as well put it on a credit card!
You can get a small business loan at FAR better terms elsewhere: https://www.valuepenguin.com/average-small-business-loan-int...
So it seems like the main reason you'd go with Stripe Capital is that they've made the whole process practically effortless.
But one thing strikes me as odd about this whole arrangement. The better a business performs, the quicker it is able to repay the loan, and the higher its effective APR becomes! It's essentially a prepayment penalty in disguise. So you'd better make sure the loan doesn't help your business too much, or you'll end up getting hosed by the loan fee.