I hated Hellgate: London.
The character classes themselves are decent enough, but each one has a ton of talents that are either outright worthless or extremely situation. The different levels are literally just copy/pasted (there's only a small handful of environments, and you'll see each one of them a mind-numbing number of times before reaching the end cutscene), the enemies are every bit as much copy/pasted as the environments (and you thought World of Warcraft was bad about this!), and the gameplay itself is clunky and unchallenging at best, glitchy beyond recognition at worst.
The glitches seem especially prevelant when played online... stuff like you seeing player character models getting stuck on environment, particularly the subway tracks in quest hubs, even though the player who is "stuck" is still moving around perfectly fine being a pretty common one. Another pretty common glitch occurs when holding down the fire button too long on flame damage assault rifles... the result is other players getting stuck hearing your gunfire sound effects looping indefinitely, until you reconnect to the game or go through a load screen.
And to top it all off, the game isn't even challenging. Like... at all. I played a ranged firearm-based character, a melee character, and a pet-based character, it was a complete cakewalk for all three.
I had very high hopes for Hellgate: London, and was thoroughly disappointed by it. It was probably one of the most disappointing gaming experiences I've ever had in my like 20 years with this hobby. It promised a hell of a lot, it had a developer working on it that I'd trusted because of their time with Blizzard, and it pretty much fell flat on every single promise that it'd made to us gamers.
If I'd known then what I know now about the game, I wouldn't even bother playing it for free. Seriously. Remember, even a free game costs you time. Time that you could be spending on far better games.