Vertical, no, as others have stated.
But I'll take the minority opinion as for the Jakks games themselves. Yes, they are not perfect arcade representations. But they are pretty damn close and certainly a lot of fun.
If you're looking for casual entertainment and want:
* Zero boot-up time
* Zero configuration effort
* Zero chance of software configuration corruption/errors
* Idiot-proof menu system
and are tolerant of good, but not perfect, ports of the games, then the Jakks units are definitely the way to go.
As others have done, you can also combine multiple units through a switchbox to get more than 5 games in one cabinet.