For those who have been interested in Bordeaux wines for some time, I will not say anything new here. I am writing this for those who are just starting to get their bearings. I, for one, would have found the information useful when I was first starting out. At the very least, I would have saved a lot of money.
Vintage matters, and it matters a lot. The weather has a big effect on the quality of the grapes in any given year. Which in turn will inevitably be reflected in the quality of the must and eventually the wine itself. Of course, it may be that a particular location or winery manages to make better (or worse) wine in a given year than it does elsewhere. Generally speaking, however, the quality of each vintage of Bordeaux red wine is as follows (I'll be brief):
2023 - looks promising
2022 - exceptional
2021 - very good
2020 - excellent
2019 - very good
2018 - excellent
2017 - average
2016 - excellent
2015 - excellent
2014 - average
2013 - bad
2012 - average
2011 - average
2010 - excellent
2009 - excellent
2008 - average
2007 - average
2006 - average
2005 - excellent
I don't go into older vintages, the wineries (with a few exceptions) won't pour wine more than 15 years old anyway. Nor do I intend to go into this topic at length here - those who are interested in detailed information can certainly find specialized websites on this topic.
The above information does not apply to white wines and certainly not to sweet wines from Sauternes. There it is completely different.