On Tapatalk, so keeping it short.
After playing them:
No headphone jacks on either the arcade or game gear style.
Controls feel better than expected.
All the games I tried so far on the arcade one suck pretty bad. Most are a single play field. Some are stupid simple, like a dinosaur catching falling balls.
The games on the game gear style one are a bit better. They kinda look like generic NES games. The control is only 4-way.
Conclusion: The games aren't worth anything. The cases are worth it for hacking or decoration.
I saw a teardown of the arcade one. The screen is mounted on the main PCB, so I think it would be a PITA to reuse. The housing and controls are very nice though and on a separate board.