So there are a couple different ways of looking at this. One, did the conquest affect ordinary Gauls: Yes, quite a bit. Pliny the Elder says that 1,192,000 died during the Gallic Wars, and while this is undoubtedly an exaggeration and shouldn't be taken as geographically uniform (ie, some areas were relatively unaffected, some were depopulated) it does underscore how catastrophic the wars could be. One million, after all, is going to be a pretty hefty chunk of the population. How exactly do these losses happen? We might think to the Swahili proverb that when two elephants quarrel, it is the grass which suffers. The "big actions" which Caesar mentioned should only be seen as the tip of the iceberg in terms of conflict and human suffering. Even within Caesar's text we frequently see reference to "foragers", which is after all a bit of a euphemism. And if we take a broader, comparative approach we can see the way that, say, the Australian and Japanese armies press ganged locals into working as porters in Papua by displays of violence in villages, a strategy still used across the world today. And, through undoubtedly the same processes, ancient wars produced refugees just as surely as modern ones do. One example comes from the funerary inscription of Plautius Silvanus, who led a devastating campaign across the Danube in the 60s CE and, perhaps not coincidentally, settled around 100,000 "Transdanubians" within the empire. The chains of refugees may have had the expected effect of further the deprivation in other areas, and we can thus imagine the wars leaving shockwaves far beyond where any actual battles are being held.

After the war, though, you are a bit off of the hook. The Roman state, as one might imagine, was somewhat AWOL for the next couple decades. This should not be taken to mean that there was no Roman presence--The Aquitani, for example, revolted around 39 BCE and were put down by Agrippa, so the province was not abandoned. But by and large the empire was too preoccupied to get down and dirty with reorganization until after Antony was defeated. But even before reorganization and incorporation the hand of Rome was felt to some extent--the revolts that occurred are often blamed on "Roman merchants" and although this is a bit difficult to parse we can imagine that being taken advantage of can cause widespread advantage.

After full incorporation, the administrative nature of the empire would have certainly been felt. We don't have primary sources for Gaul, as Tacitus for example only mentions "heavy debts" that led to the revolt of Julius Florus in 21 CE, but we can get an idea of some of the grievances by looking at his description of some of the reforms of Agricola in Britain (Agricola, 19):

He lightened the exaction of corn and tribute by an equal distribution of the burden, while he got rid of those contrivances for gain which were more intolerable than the tribute itself. Hitherto the people had been compelled to endure the farce of waiting by the closed granary and of purchasing corn unnecessarily and raising it to a fictitious price. Difficult byroads and distant places were fixed for them, so that states with a winter-camp close to them had to carry corn to remote and inaccessible parts of the country, until what was within the reach of all became a source of profit to the few.

Not to mention a variety of complaints against the abuses of power by centurions and soldiers. We can see these grievances manifested on both a large and a small scale--one example I love is that a Roman official's grave in Gaul was desecrated to insert a curse tablet as punishment for his abuses in office (interpretation from Faroane's Magika Hiera). I doubt rather much that the imperial legate would have personally knocked on a Gallic door and kicked him in the shins or anything, but we can imagine how the systems of tribute and taxation combined with the imperial nature of the military authority of Rome might have knock down effects affecting even the very lowly.

If you step back and think in terms of centuries, the Roman period was very different from that which came before, and enormous social changes from the monetization of the economy to the way houses were built to the development of the true city occurred (and this is where we can really use archaeology, rather than history). But this is somewhat outside the scope of your question and so I'll stop here.