Quickleaf
Legend
One of the fighters I created has both linguist and observant. He can read lips of 5 different languages from a fair distance. Helps when trying to keep an eye on a target in taverns, and not have a rogue.
I applaud you making such a fighter character

This is the "fighter is defined by feats" argument that often comes up in discussing the fighter's non-combat functionality. While it may be true at your table due to your group's play style, I believe it's a flawed argument when it comes to design for 3 reasons:
First, if you have a consistent gaming group that is mindful and considerate ("hey, John is running a fighter with observant & linguist feats, so nobody else takes those feats so his fighter PC can maintain that uniqueness"), then you are golden. No problem. However, if you have a rotating player base – e.g. Adventurers League, a West Marches-style game, or something else – the DM likely has no foreknowledge over what characters are brought to the table, and thus no ability to enforce the uniqueness of a fighter by virtue of feat choices. You might end up at a table with a druid with Observant and a wizard with Linguist, and bye-bye your uniqueness.
Second, feats are optional. In such a no-feat game, the fighter simply gets two more ASIs (at 6th & 14th levels)...but abilities cap out at 20...so what those extra ASIs actually translate to are reaching 20 in your primary attribute a few levels faster...and having one other attribute a bit higher. Is that really unique? I'd argue "no."
Third, the rogue also gets an extra ASI (at 10th level).