Monero has a private blockchain, in the the sender and receiver are always protected from knowing each other, but (correct me if I'm wrong here) the amount of money moving across the blockchain is still visible in some respects.
If someone sent 300,000 Monero across the blockchain, then observers would be able to see that a large amount of money moved today but not be able to pin it down to a particular user or transaction time (with proper mixin settings)
I thought that with the new CT ring developments coming out, people wouldn't be able to tell what amount of monero is being transacted unless you have the right key which shows you the amount for that particular transaction? Wouldn't this be a non issue with the upcoming developments?
In theory yes. It has not been implemented yet into monero so testing needs to happen over months to come.
For now AP is right you can see how much is moved and when. But not who sent to who specifically.
Also you can't really tell it moved between two people. Much of it could be change going back to the sender and it could be someone moving from one wallet to another.
Above comments about CT are correct. However, even with CT, using math an observer can still verify that the coins spent are equal to the coins received. You just can't tell the number.
This is assuming you have the "Amount Key"?
No. The equality sum(in)-sum(out)-fee=0 is independently verified by every node or any observer without any key.
To explain in simplified terms how this works, there is a random blinding term x, which is secret.
Ignoring fee here for simplicity:
hidden_in = real_in + x
hidden_out = real_out + x
Of course real_in - real_out = 0
But hidden_in - hidden_out = 0 i.e. (real_in + x) - (real_out + x) = 0 also
hidden_in and hidden_out are visible on the blockchain.
(Magic crypto math means that you can't do something silly to break this like solve for x.)