The Galaxy Class could easily and sincerely be called the most complex vessel in Starfleet history. Many books have been written both praising and condemning the vessel for its many attributes and faults. Unfortunately, looking back on it after 30 years, it's apparent that the vessel could ultimately be called a controversial design.
In no uncertain terms, whilst the Galaxy class is doctrinally a battleship and treated as such, it was never actually designed to function as one. Sporting enhanced weaponry in virtually identical positions to the Ambassador class vessels the ships were intended to replace. The most notable difference was the swapping of the Ambassador's multi-strip phaser arrangement for two extremely long strips on the dorsal and ventral sides of the saucer section, the longest ever fitted to a vessel up to that point. A bow-oriented multi-shot torpedo launcher and stern oriented launcher could be found in the secondary hull. The shielding of the ships was incredibly advanced and potent, as well as being easily modified to suit an individual ship's mission profile. Famously the one ship, the Enterprise, flew into a star to cook a Borg Minelayer during one mission, surviving with minimal damage.
Unfortunately, whilst the Galaxy class did sport a respectable armament, it also sported something many would consider to be a huge mistake for the class, a permanent civilian population. Whilst other vessels most certainly carried civilians, largely crewmember's families, scientists or simple passengers, the Galaxy Class was intended to function simultaneously as a starship and a nomadic colony for up to 10,000 people. This population would largely be expected to remain in the saucer section and away from the more sensitive areas, but civilians have a remarkable propensity to go on walks and, on starships, end up in places they shouldn't be. It's believed by Starfleet Intelligence that most of the technological secrets of the USS Galaxy were in the hands of the Cardassians, Romulans and Tholians mere hours after she departed on her first mission. Unfortunately this would not be the only problem the vessels encountered.
In 2364 the second vessel of the class, the USS Yamato, was destroyed due to antimatter containment failure after several hours of continued computer failures. Out of the 2,500 souls aboard there were no survivors. Things would get worse in 2367 when the USS Victorious, the newly built fourth ship, led the fleet at Wolf 359, making up a quarter of the 10,250 dead on her own. Following this the third ship of the class, the USS Enterprise, was destroyed in combat with the Duras sisters, albeit with most of her 1,500 crew and civilians surviving. And then, to top it all off, the USS Odyssey, having left her civilians behind, was destroyed by the Jem'Hadar in the Gamma Quadrant, with her entire 1,100 strong crew being killed. Out of the originally planned 6 ships, 4 were destroyed, 3 in combat. It was this atrocious level of combat deficiency which saw the sole surviving vessel, the USS Galaxy, immediately drydocked following Enterprise's loss for a complete armament and shielding upgrade, with the 6th ship, the yet-incomplete USS Venture, receiving even more extensive upgrades.
Following this refit and design alteration, the two vessels would become truly formidable warships in their own right, superior in firepower to even the Sovereign class. Simultaneously their huge civilian spaces were ripped out and the civilians rehoused on starbases, being converted into holodecks, replicators, cargo stores and barracks, allowing the ship to function seamlessly as a cargo ship, destroyer tender and battleship. These modifications are arguably what saved the vessel from being written off as a complete failure. With tensions with the Dominion exploding into full scale war new ships would be built en masse to fill both the battleship and logistics role, as both were massively strained during the Dominion War. Many of these ships, nicknamed "war hotels" by their crews, would become famous in their own right, being the ships that broke the Dominion's back. Famously the USS Challenger led three separate task groups through Dominion Lines during Operation Return, letting the smaller ships through before turning back to keep the Dominion occupied. It can be argued that the Galaxy class is the ship that won the Dominion War looking back on it.
And so, with the white flag raised and guns silent, the Galaxy class has since returned to its exploratory duties, but the question still hangs over them… what exactly do we do with them? There are admittedly superior ships in the exploratory roles, and so a number have been sent to the breakers already after substantial incidents. A number do remain in active service, but with Starfleet policy shifting away from exploration, it seems the time of these once impressive ships is sadly drawing to a close, far sooner than their originally intended withdrawal date.