I brewed a Trappist 9 months ago, each bottle I drink gets better.
Around the same time, I brewed a Pils, and the flavors are smoother, cleaner, and somehow hoppier than 4 months ago (even though the "word" is hopiness fades with time).
I brewed a IIPA, after four months, it started losing deliciousness- luckily it was so good I had only a few bottles at that point.
To me, ageing beer is one of the most fascinating parts of homebrewing. I have found the vast majority of them improve, up to a year (though I have few that last more than a year anyhow).
I very much want to brew some huge barleywines, RIS, and Quads, and let them sit for years. Don't know if I have that much patience.