Been using them for a few companies the past year and a half, and migrated more and more of my stuff over to them, it offers the simplicity and clarity of "stripe at the beginning" while already being backed and owned by a major bank (BPCE, 2nd biggest banking group in France). They don't have all the bells and whistles of current Stripe, but for most projets we don't need that anyway.
And there is no bullshit about random overnight account closure with no recourse.