You can start with a lot of what this guy tweets: https://twitter.com/twobitidiot/status/946752692281540608
But there is more. Watch the videos I linked in the article as well (new) and you can simply google it.
That is all besides the simple logical deduction: Ripple is a for profit company that sells a service to banks supposed to replace Swift. Swift itself is fast, cheap (to banks, maybe not to the end customer but what to banks care about them) and owned by the banks. Why would they switch to a fast system owned by someone else that gets more expensive the more people use it (if banks actually had to buy public ripple token their price would rise massively, while the system is designed for Ripple itself to be the fee of the transaction — this cannot work. It is now already too expensive to transact that way).
So yeah, I am not making this up — it is easy to find more on this if you want to via google.