If I am not mistaken the OP is asking about Jodo Shinshu, founded by Shinran Shonin, who was indeed initially a member of the Tendai school.
I frequented a Shinshu temple for a length of time back in 2000 or so.
I was particularly impressed by the wisdom in the Shoshinge. The teachings of Amithaba's Primal Vow were certainly inspiring as well, but sometimes I felt the Temple weighted down by a certain... lack of ambition might be a good description.
I was disappointed to see it giving way too much space to a Spiritist lay speaker as well. He co-opted the teachings like they had been found uncared for in some dark alley.
So, in a nutshell, it can be a beautiful practice if you are lucky enough and/or bold enough. But a lot depends on having the good fortune of connecting with sufficiently skilled teachers and practicioners, of which unfortunately there are never quite enough.