It advertises itself as "from all fields of science" -- does that includes fields like economics? Sociology? Political science? What about law journals? In other words, is the coverage as broad? And if it doesn't include certain fields, where is the "science" line drawn?
And I'm curious if people find it to be as useful (or more) just in terms of UX, features, etc.
As for coverage, I think it focuses more on the life sciences, but I'm not positive about that.
Now for the less great.
They are pushing the concept of "Highly Influential Citations" [1] as their default metric, which to the best of my knowledge is based on a singular workshop publication that produced a classifier trained on about 500 training samples to classify citations. I am a very harsh critic of any metrics for scientific impact. But this is just utter madness. Guaranteeing that this metric is not grossly misleading is nearly impossible and it feels like the only reason they picked it is because Etzioni (AI2 head) is the last author of the workshop paper. It should have been at best a novelty metric and certainly not the default one.
[1]: https://webflow.semanticscholar.org/faq/influential-citation...
Recently, they introduced their Semantic Reader functionality and are now pushing it as a default way to access PDFs on the website. Forcing you to click on a drop down to access plain PDFs. It may or may not be a great tool, but it feels somewhat obvious that they are attempting to use shady patterns to push you in the direction they want.
Lastly, they have started using Google Analytics. Which is not great, but I can understand why they go for the industry default.
Overall, I use them nearly daily and they are the best offering out there for my area of research. Although, I at times feel tempted to grab the data and create an alternative (simpler) frontend with fewer distractions and "modern" web nonsense.
My conclusion is that any such system needs to be "complete" or almost complete to be useful. By system, I mean a service or some handcrafted system where I could track anything. In all fairness, Sci-Hub partially fits the bill here and it's a big plus to society.
But the point is Google Scholar is complete in the sense that with a high probability I will find any paper I'm looking for along with reliable metadata. That's great, but the fact that they go above and beyond to prevent sharing that data is IMO backwards, against all academic research principles and this should raise questions within the research communities that rely on it.