As much as I wish for the update to be finished, you do realise that Johnster and the team have been trying to make Beta 1 as good as possible without any rush. Besides, he's also busy with his life, which causes the long wait. He wants the game to be good, so he's taking a lot of time and putting in effort to ensure Beta 1 is as good as Alpha 6.
There isn't a lot of gameplay for now; however, Progress Update #19 will change a lot, and it will hopefully make up for the long wait.
Beta 1 will likely feature Floor Maker and Adventure Mode floors, so multiplayer and everything else will probably not be included in this update, as he is likely saving them for a future update due to the foundations. It's more like a small demo of V1.0.