Iirc there were 8 chiplets on the cell die, one was disabled for yield rate and one was dedicated to the os itself, leaving 6 of them for gaming.

Then they had the super riced out rsx (Nvidia GeForce 7000 series) for the GPU, but there wasn't really a "main" CPU was there?

The Cell had a PowerPC core (the Power Processing Element) as its main CPU, alongside the Synergistic Processing Element co-processor units.

I think the 360 had a regular homogeneous tricore CPU, so programming it was just normal multithread programming. As you say the PS3 had several auxiliary processors that all needed to be told what to do in specific, non-portable ways, which is what made it inconvenient to work with.