I'm not perfectly happy, there's not not much impact being unhappy is likely to have. Once a company makes a huge announcement like this, displeasure from the customer base is unlikely to cause them to change their minds until either they discover the change was a HUGE mistake and upsets lots of their customers and they lose significant market share OR they're forced to change because they go bankrupt.

Being unhappy isn't likely to change Opera's decision, of course, but... the reaction to Opera's decision is likely to influence other players.

For example, the difference between "bring on the monoculture" and "this is a sad day for web standards" is likely to influence Mozilla's future direction, both directly and indirectly (via the choices web developers make in supporting or not supporting Firefox).