Stereo replacement

whats up all?!
I have a 99 escalade and have a pretty nice ($450) new deck I would like to put in it. Just wondering if anyone else has replaced the head unit ONLY ?? If so did it sound as good as the factory radio did. Im just a little worried about it because the factory bose sounds so damn good I just dont want to spend the money on an install to have the sound quality go down...
Or if you have had any other issues related to this topic let me know also! (I dont care about the onstar)

Thanks !