Whether or not the referendum can be considered to be "democratic" highly depends on who is doing the considering and what their definition of "democratic" is. The election commission surely seems to think so, for example, while parts of the opposition do not.
There are, however, some points that may or may not influence the consideration depending on your definition:
- Turkey currently is in a state of emergency, giving additional powers to the government and the president.
- Dozens of opposition leaders, including influential members of parliament were imprisoned before the bill that underlies and enables this referendum was introduced, and thus unable to vote or take part in the discussion; for example a dozen MPs from the HDP, including the entire party leadership are currently in prison.
- State-run media outlets gave an unequal amount of media coverage to proponents of the "Yes" and "No" camps; the amount of time allotted to campaign coverage of the "Yes" camp outnumbers the time allotted to proponents of the "No" camp about 10:1, the HDP (party of the Kurdish minority) received practically no coverage at all.
- On the flip-side, hundreds of independent media outlets were closed in the run-up to the introduction of the bill and the subsequent campaign for the referendum.
- Dozens of independent, opposition, or critical journalists were imprisoned.
- Simply indicating that you support "No" may get you arrested on a treason or terrorism charge.
- Hundreds of judges that might have opposed those imprisonments were fired, or themselves imprisoned.
- "No" campaign events were regularly victims of intimidation, both passive and violent; police were often slow to respond and sometimes even were the ones doing the intimidation. State-run utility companies shut down power to venues were events of the "No" campaign were held, municipalities run by a pro-"Yes" government prohibited campaigning for "No".
Note: I am deliberately restricting this list to the campaign and election run-up, since events from the election itself are still unclear and in flux.