What were the other major flaws?
* Partially incompatible with regular IBM PC software
* Max 128K RAM
IBM likely did this stuff on purpose to avoid cannibalizing PC sales, but it ended up killing the Jr. Later on Tandy would borrow the PCjr sound and graphics hardware (superior to a normal CGA PC/XT) for a line of more successful personal computers.
IBM sold a 128K memory expansion sidecar to bring it to 256K. There is also apparently a way to swap in denser RAM chips to make it 512K (640K total).