I may be overcomplicating this but I think there are two elements to the question.

In the first place, yes, the Constituent Assembly elections of November 1917 were conducted on the basis of universal suffrage and are considered by historians to have been free and fair. There are some accounts of fraud but these were fairly localised and of a petty nature (eg handing out ballots with only Kadet lists to the illiterate in some villages). Arguably these elections were the freest in Russian history.

That said, the election did contain the rather sizeable flaw in that it made no account of the split in the Socialist Revolutionary party. There wasn't enough time to reprint the ballots between the party's split (at the Second All-Russian Congress of the Soviets, 07 Nov) and the elections 25 Nov. The significance of this was that the single SR list that was issued favoured the Right (ie anti-Soviet) SRs who were more established in the party's provincial apparatus at the time of the split. Given that Left SR policy (pro-Soviet and in favour of immediate redistribution of land) was almost certainly the more popular with the peasantry, who comprised the vast majority of the electorate, this introduced a pretty big flaw into the composition of the Constituent Assembly.

But step back from the elections and there is a broader question as to the democratic nature of the Provisional Government. The first thing to note is that this was never an elected body; elections to soviets and local dumas continued throughout 1917 but the composition of the government was not determined by these. Nor was it responsible to any parliamentary body. (Indeed the Provisional Government had a very ambivalent relationship to the old State Duma, actively sidelining the latter.) Despite that, and the occasional use of political repression, for most of the year Russia could legitimately claim to be 'the freest country in the world'.

This did sour somewhat towards the end of summer as the country polarised and the various governments fell apart. By the time of the October Revolution (when the regime was well advanced in terminal decay) Kerensky, who increasingly styled himself as a Napoleon figure, was effectively ruling by personal decree. Sukhanov (who was a far from impartial witness) described the feeling that the "last coalition of ours was a gang of usurpers who had seized autocratic power through private agreement among a couple of dozen men". Really, from late August onwards the Russian government could hardly be called functional, never mind democratic.

So the picture is, as always with Russia 1917, mixed. Elections to the Constituent Assembly were free (if flawed) and the Provisional Government wasn't notably democratic, and increasingly less so, but ruled over a pretty democratic country.

Sources: I'm not a massive fan of Figes' A People's Tragedy but he's pretty good on the decay of the Provisional Government (he has a particularly good eye for Kerensky's foibles). Sukhanov's Memoirs are an essential/great read. Rabinowitch's The Bolsheviks Come to Power gives a good sense of the grassroots democracy that flourished in 1917 (often contrary to blithe foreign assumptions of 'Russian autocracy'). Finally, the details Constituent Assembly fraud came from Kowalski's The Russian Revolution.

[Edit: Tidied up language and corrected a few spelling mistakes.]