A lot of the criticism I’ve seen thus far falls into two categories:
Users complaining that their favorite source is scored poorly
Users complaining that the ratings have various sources of statistical bias
The ones in the first group I think should take it as a wakeup call that they are either headline shopping or missing out on other perspectives of current events. This is especially important on the international stage where armed conflicts will naturally produce two opposing accounts (and lots of propaganda).
The second group have a point - MBFC isn’t the end all be all, but it’s certainly better than nothing. Having meaningful bias measurements for each relevant scale would be impressive but way beyond what MBFC aims to do.
So all in all - I see this as a very positive change