It's a board with letters on it. Nothing more, nothing less. People have been making them for generations with posterboard, markers, and a shot glass.
I collect them. I've used them with mixed results. >95% of the time, I'm convinced that the 'entities' that come through are nothing more than parts of the user's mind. Whether they're truthful, friendly, hostile, etc. depends on the user themselves. Most people don't know what's down there and aren't prepared to meet what they find, which IMO is where a lot of the weird stories come from.
The other 5% or so? There's something there. That's not usually the case, though. It's just that the messages through the board seem like something external when they usually aren't.
If you want to try your hand with these, go for it! Just remember that YOU are the one in control, not the board. Even if whatever comes through seems alien, it's probably not. It is your responsibility as the user to weigh the information (if any) that comes through and to use that information. People blame spirits and/or the board when in reality it's on them as a user. In that respect it's no different than Tarot. What you do with this is totally up to you.