It seems like there's a new trend popping up: Newsletters and paid newsletters.
I prefer to read content using a news reader, with which I can subscribe to countless RSS (or JSON) feeds. I can also decide when to consume new content and am not bothered with reminders etc. that there is new content available. Full freedom on my side.
Newsletters however popup in your email inbox and create pressure. The newsletter stays in your inbox, always reminding you, you haven't looked at it yet. It interrupts your productivity. (Or at least this is how I feel.) I tried subscribing to newsletters, but always decided to unsubscribe again, because those mails annoyed me just too much.
Another reason against newsletters is, that they don't stay. Only those who have subscribed to it can read it. Information written in it (that may be helpful to others) is lost for people subscribing only later or not subscribing at all. It isn't indexed by any search engine. If someone searches for something you have written in your newsletter 5 years ago, they won't find your words. If you would have published it on a blog, it still may be available.
So, my suggestion for everyone wanting to start a newsletter: Create a blog and offer to also send all new posts via email. Or at least have an available archive. If you want to start a paid newsletter, offer a paid archive.
Another bonus of that approach is, that a potential subscriber can evaluate first, whether your newsletter is worth to subscribe to.