I do think there is some room to constructively criticize them. Godzilla seems to want them to perform miracles, but I think they're doing a lot of good in the capacity they have served so far. They are actively using the powers of Congress as they are intended for the benefit of common people. It cannot be overstated how awesome that is.
However, their particular ideology is not yet popular or particularly powerful across the country. Most of the Dem wins in 2018 were center left so I'd constructively criticize them to be more mindful of where the country is. Their Twitter following, no matter how large, is not a particularly good indication of where most of the country is. I implore them to keep pushing the population in the right direction, but be mindful of where it is now. That's what Pelosi is doing and sometimes I feel like they unnecessarily criticize establishment Democrats out of passion, whereas Pelosi is correctly trying to calculate. Passion only takes you so far, so fast.
I worry socialism will be the effective hammer that delivers another Trump win. They can't serve him that hammer on a platter.