The issue that this party will have to be careful of is who actually joins it and therefore influences it.
They have Corbyn at the top. Okay, everyone's cup of tea at all, but at least he is a well-known figure.
Below that, it remains to be seen.
Their big risk is that they attract a lot of people who are too interested in politics already. That makes their approach nowhere near broad enough because then they are only speaking to other people who are already too interested in politics.
Parties on the left are more likely to do this anyway, because they have a habit of placing their principles ahead of their electoral chances. Parties on the right or centre are more likely to just want to win so will seek out what the voters want. Parties on the left will try to educate voters, forgetting that most people have no desire to be educated.
It becomes more and more of a problem if those people involved are interested in something very narrow that most people simply don't connect with at all. But that issue is why they got involved so they aren't giving it up in a hurry.
Ultimately we will wait and see what happens but I'm not sure the signs are great.