One of the major differenciating factors between CEX and DEX is the UI/UX. While the developers of CEX build something user friendly, DEX doesn't consider user friendly as priority. This easy to use situation of centralized exchanges tend to invite new commers to CEX rather than DEX. This is why so many newbies infact uses exchanges as wallets. If you can build an good UI, it will be a plus.

Also, don't fail to consider how you handled liquidity problems.