Obamacare has mailos and chesronos. Unfortunately the mailos and chesronos are tied to each other so that you can’t get one without the other (e.g. covering pre-existing conditions requires a mandate).
If you do not have insurance through your employment and if your income is low enough, then Obamacare makes you better off.
If you have insurance through your employment or if your income is relatively high, then Obamacare leaves you worse off. My health insurance costs through my employment have increased every year since the ACA went into effect and the coverage has gone down (i.e. higher deductables, higher co-pays, higher-co-insurance).
Overall, more people have been hurt by Obamacare than gained from it (because 70% or so get their insurance through their employment) but the hurt has been relatively minor to the gains.
In short, repealing Obamacare will help more people a little and hurt fewer people a lot.