I am glad that there is finally another default theme again but currently I am disappointed in the Twenty Nineteen theme, it is too minimalistic, less flexible, less colorful, has fewer features even lacking basic features like: header images, custom fonts and custom font sizes, the automatically display first image in a post option which is a must for me because I use the excerpt option so without that my home page / archives page looks bare and boring and the same without my hotlinked images showing for each post, preset color palletes, sidebar, and more, has more bugs, et cetera than maybe any previous default WordPress theme.
The spacing between sections is too large (especially the space before the widget area) and is inconsistent, post / page / widget titles are too large (even larger than the blog title and blog tagline) while the blog title and blog tagline are too thin and small in comparison, the site logo is too small, when using excerpt mode there is no text to let readers know that there is more text to read and there is no link there that will take you to the full post, and more.
Fortunately WordPress.com support actually responded to my reports and have submitted my issues to the developers (thank you very much for the good support that helped to restore some of my faith, and gave me more encouragement to start reporting issues / bug / recommendations again), and maybe some or most of them will be fixed; but some of the common necessary features / options are likely to never be added to this theme which will possibly make it less versatile out of the box.
I think that a default theme should come with enough options / features to make it usable for most people and / or be designed in a way that will be acceptable for most people; and it is the least colorful default WordPress theme ever so it lacks a lot of customization / life / uniqueness / personality / et cetera.
One good thing that I can say about this theme is that it at least looks somewhat modern and is easier to read thanks to bigger text and better fonts in some areas (some are too big).
If the automatically display first image in a post option is not added, then like with the Twenty Seventeen theme, I will not be able to use it unless I start using the more tag; and that would make it the second default theme in a row that I barely used and could not use because it lacked common and important features / options that I need in a theme and would mean that things are getting worse when it comes to developer trends in new themes here at WordPress.com.
To make it worse there was no Twenty Eighteen theme so I have been waiting for even longer for better free themes and if things are not improved with this theme that will make it three years of unusable default WordPress themes, which is terrible, because usually the default themes were my fallback each year and I usually could rely on them to be general purpose themes that fit enough of my needs to use when most of the other free themes do not meet my needs; but unfortunately things have changed, and now the default themes have gotten worse / gone further from my needs / become unusable.
To make it even worse fewer free themes have been made than ever during this time period after the release of the Twenty Seventeen theme, and the few free themes that were made were mostly unusable for my needs thanks to the strange new developer trends in theme design which are moving further and further away from my needs in a theme; and so my options have been more limited than ever when it comes to free themes made within a year (I try to only use themes that are not more than a year old when possible, and I like to change themes at least every year).
I hope that the free theme situation improves or eventually there may be no usable new free themes on WordPress.com for me to use in the future that meets my simple needs in a theme; my needs in a theme are pretty simple in my opinion and so it is confusing to me that it is becoming so rare for themes to cover simple needs that I thought should be in any theme that needs to be more general purpose / flexible / versatile / accessible / et cetera.
I would give the Twenty Nineteen theme a rating of a 3 out of 5, I am glad that another default theme was made and I want to see it improved, if they fix some of the bugs and other problems it could get be a 3.5 out of 5; and with some other improvements like: adding all the customizer options / a large site logo / various other adjustments then it could be an even better theme in my opinion like a 4 out of 5.