Also, there's definitely a culture of silence going on here when it comes to Hela, I'm utterly convinced of that. I think Marvel have told reviewers not to say too much about her at this stage for fear of spoilers inadvertently slipping out. From what we've heard, there are some pretty big surprises surrounding the character which clearly means that they're going to want to keep her much tighter under wraps than other characters in the film.
If Hela really was an underwhelming villain and Blanchett was disappointingly underutilised, you bet your ass that the reviewers would have been saying that by now, but when anyone does actually say anything about her or are asked directly about her, it's always incredibly positive. She's been called scary, intimidating, funny, charismatic. I've even seen a couple of people say she's the best MCU villain to date. So why the general silence about her otherwise? It's all very fishy to me.