The game never was jaw dropping, it was notoriously and righteously panned by critics on release.
Dumb AI being one of them, even for being zombies.
Dated visuals i believe was another.
However at the time there weren't many, if any pure zombie FPS games to be had so this fit a nice niche at the time before Left 4 Dead, Dead Island and Dying Light.
Campaign is average at best but still serviceable, the real fun was multiplayer.
I dont mean the default MP the game shipped with, it was just a barebones deathmatch or a wave survival mode (on tiny maps), but the modding community improved on that, there were alot of cool maps made for the game, large too.
A few things i always remember about LOTD is the punchy head popping revolver and the worst shotgun in videogames ever, it could miss at point blank!
Anyway, the usermade maps, with added content thanks to the Unreal Editor, they made the mall from Dawn of the dead -78, the bunker from Day of the Dead (with alot of zombies in the elevator!)
An infection mode was added so you could get infected and eventually die only to rise again (not unlike No More Room In Hell, the Source game).
They created some new weapons to be used, some maps were just a playground, others were focused on pure survival horror.
Like a NOTLD map with doorways and windows that could be barricaded. Lots of fun.
The effort put into the multiplayer maps really made the game shine, been years since i played it but i spent quite a good chunk of time with LOTD back in ca 2005-2007!
Its a chunky game, i mean that in both good and bad ways, it does stand out to me for being the first proper "Romero zombie" game and it left a small legacy due to that.
To see it added to GOG is not an absolute must, but more of a "nice to have", worse games do exist.