It's almost never going to be just another day. For a start, the acquiring company is almost certainly going to immediately stuff fucking with your benefits. Your projects are incredibly unlikely to survive- so if you care about what you're working on, forget it. If your project does survive be ready for a massive influx of new people all of whom have their own ideas of why the acquisition happened and what your project was for. Oh and because acquihires almost always happen where the acquiring company is a behemoth you're going to subsumed into a massive bureaucracy that is clearly not what you signed up for in your original job.
