I failed to keep this up, but I should note that Inslee, Buttigeig, Sanders, and O'Rourke are all official now.
Sanders is a known commodity at this point, and has done work t shore up his foreign policy weaknesses. He just isn't the only thing in the field and has a lot of baggage. But given the rules of the Democratic system, the fact he has a core fanatical base might get him in through other people splitting votes.
Buttegeig is really interesting, with one of those "hard to pin down" stories - (Veteran, gay, mayor in Indiana). I don't think he will win, but I think he will be an interesting voice in the debates if he qualifies.
Inslee is running on climate change and not much else, I don't think he will last long.
Beto is going to get a LOT of press up front, and it seems he is making me eat my words about running as "The Moderate" because it really does seem like he is going to position himself in that lane even more than Klobuchar (who is going more for "I can reach across the isle and make deals"). Beto and Biden might end up in a straight up competition for a similar group of voters, with Beto skewing younger and Biden skewing more "fond memories of Obama".