Really? I thought you replaced it because the 7.62 NATO round did not agree with the gun's "full auto" setting. The Uzi was the gun that didn't agree with the Middle East.
Nobody fires full-auto anyway, only in short bursts. You can't control any weapon on full-auto, except MGs, and even then, non-fixed ones stray. As for the Uzi - you can rape that little thing up the arse, and it still won't betray you. It's also prone to misfires because of its simple, rugged mechanism. Besides, the Uzi did not replace the FN, as it's a 9mm SMGm, and the FN-FAL is a large assault-rifle.
It did, however, fail like most weapons during sand-storms and the like. Only the FN-MAG (a light MG, 7.62mm) kept on working properly... but that's a 12-odd kilo weapon.
The Uzi's main strength were its size, simplicity of operation and price. It was used in urban warfare in the 1967 fights in Jerusalem, but was later replaced by more powerful weapons (the Galil and eventually the M-16), and in the 1970s-1980s became a weapon for non-combatants. It is no longer in use, except by specific SF teams (much smaller, newer models) and law enforcement (rarely, too). It was used by mechanised personnel (armoured corps), but was replaced by the Galil SAR ('short assault rifle') not long after.
Soldiers fighting in the desert often find the AK family to be much more reliable. Israeli soldiers during the Yom Kippur war in 1973 also picked up AK-47 from defeated Egyptian soldiers, and used them to effect. This, in part, led to the design and manufacture of the Galil. The Galil isn't a bad weapon, it's very reliable (if heavy and uncomfortable), but the M-16s were
so much cheaper, and still are to this day - making the introduction of the clearly superior Tavor more difficult.
The Uzi's prime glory was mostly in foreign export and action films.
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When fighting monsters, be wary not to become one... When you gaze into the abyss, it also gazes into you." -
Friedrich Nietzsche