I haven't heard much poor feedback regarding her plan. I think the damage was done even before she released it when she continually evaded the question on middle class taxes. If you're going to adopt that m4a approach then you better have a plan for it coming into debate season and you better be ready to go all-in on it or else the sharks are going to pounce. Like
@Warren Moon stated she obfuscated too much on the funding aspect.
Personally, I think it was a strategic error by her to even adopt m4a considering it is not genuinely her passion and most people who support that approach are going to ride with Bernie till the wheels fall off. She had way more voters to gain by trying to sell a more incremental approach that could actually get passed.