I thought it was pretty funny. Maybe it is an easier problem to solve for Solar Opposites than Rick and Morty, but I like the way they did it. Replacing a voice actor can always be jarring, but this is a funny way to do it.
I always kinda hated that Korvo just sounded like Rick, so him being voice acted by such a great actor as Dan Stevens (hopefully not as a one time joke) is a total upgrade to me. Korvo sounding like a rude but posh Brit just fits perfectly.