Hi
Good question. My answer would be yes. My daily driver is a 1020 sporting 8.1 and I test W10 on my 535.
What I expect from new builds is more stability, etc. and above Cortana going ahead (still alpha in France but already better on 10 than 8.1).
A lot of "bugs" reported here are app-related. MSN Apps are now catching up with their 8.1 opposite numbers (MSN News can finally share an article
) so I think one has really to focus on the OS to answer the question of upgrading. Apps evolve a lot faster than builds, and to conclude, I would sum it up by 2 points :
a) We need a more refined OS (stability, performance, etc.), including core features like Cortana, tile animation, lockscreen etc.
b) We need apps (some of which are "stock apps" on WP8.1) to update quickly to bring more features. For instance, I can finally choose outlook mail to show on my lockscreen notifications. Don't know if it's app or OS related.
To illustrate this, I decided to test W10 only when the office apps were available (10080). That shows how this OS/app separation is even more important on W10 than 8.1 when you have to answer the question of upgrade or not.