Nycticorax Remember Vivaldi is a newer browser which has been adding (major) features relatively rapidly. A lack of customization or fine tuning may resolve itself with time (assuming it's not from the Chromium base). Personally those are things I could live with or not notice, other things take priority.
@mdiemer - Updates may be annoying, but remember frequent updates are usually a good thing if you care about security. Changing functionality too frequently, yeah that's fair criticism. I won't specifically bring up other software/OS platforms (no need to derail this thread), but imagine if the ones that come to mind weren't updated frequently--it'd be gross negligence in security terms.
Unfortunately it's kind of a lose-lose situation - if you update often, you annoy the anti-update crowd. If you don't, you scare the security-aware crowd. The latter has a far stronger point.