I haven't tried it as a daily driver, but I have used it pretty extensively. Here are my thoughts. Overall it works very well, with the following caveats.
1. If you're not near wifi, the battery won't make it through a full day (for me at least & that is all dependent upon how good of a cellular signal you get)
2. The second biggest drawback is with texting. It works ok in a pinch, but I find myself not enjoying long text conversations from the watch. I use Siri as it's way faster than typing out replies (maybe not an issue with the new text option, but I have a Series 5), and the frustrating thing is when it misunderstands a word & you have to cancel the reply & start over. Not terrible if it happens now & again, but using it all day, it adds up.
3. Mail is hit or miss. Usually it's very good at getting new mail, but every now & then it gets stuck on one mail view & won't update for a few days. If I were using it exclusively, that would be a real issue.
4. Viewing attachments. If someone sends me a picture or a PDF or whatever, I can't figure out a way to blow it up & view just a section of the photo. It makes it hard to understand what's going on in many cases.
5. You can't move around calendar events. I do this a lot, but that's probably going to be different for different people, but once you have an appt set for 10 am, it's staying there if you're watch only.
6. You can't set reminders for your new appts. I think if you set your appts to all have reminders set automatically on your phone/mac, then it will carry over, but I don't. I want to add reminders only to certain events & that won't work from the watch.