Good graphics, fun game play and great multiplayer. Quest content is a bit bland, but killing zombies is always fun.
The game takes a large amount of direction from Diablo 2, in its style of play. With the notable exception of the option to play in the first person. Lots of monsters, lots of explosions and a very spooky environment make for hours of entertainment.
At first, and even a little now, I find the weapon modifications and upgrades system to be slightly confusing then I would have liked. However as you being to understand it, the options to modify your weapons really opens up some weapon options similar to the sockets you saw in Diablo 2.
One notable feature I really enjoyed was the fact the textures on the gear you wore would change based on what other pieces you were wearing. So no matter what eclectic collection of gear you had equipped, you always looked put together.
My biggest complaint would have to be the quests. Many will rank this game low because the quests are the bulk of the content and they feel lacking. With such a huge portion of the quests being kill quests, or collection quests, I found myself skipping over the quest text and just pressing "Accept Quest" to finally see the "Kill X Monsters" in the quest log.
Despite the quests to not be as immersive as I would like, the creative principle of the game, the futuristic play on a more sword and sorcery genre make Hellgate: London a good fun game to play.