Just went on Freedom class for the first time after years of almost solely Oasis class. Had been on Freedom before and Voyager class several times though.
As mentioned, it really depends what you like about and where you spend your time on Oasis class.
I missed Park Cafe and crossing the ship via Central Park. And we only use the Solarium, never the main pool, which will feel much smaller. But we knew that going in of course and had other reasons we wanted to go on Indy.
Anyway, I think you'll be fine. The promenade is still similar enough as are many other areas of the ship... theater, ice rink, MDR, WJ, etc.
EDIT: Just saw you were on Freedom in your signature. It will feel very similar to Freedom, just a bit smaller. Freedom class is really just a stretched out version of Voyager class.