Well it may be a bit repetitious like Bioshock, but from the looks of it the content is more apropos for the setting. It also seems to have unique weaponry like Bioshock. After reading about and seeing screenshots of the cartoony, arcadish characters of Bioshock I almost expected SpongeBob SquarePants to be in it. My idea of being stuck in a world gone wrong scenario is not kindergarten with magical healing chambers that lull you easily on to victory but a griping sense of Doom (3), another good game with such elements.
Add to that Bioshock's botched widescreen "support" and you have something that is not very modern day except that it reminds you in an insulting way that your hardware is outdated if you don't have a shader 3 card. From what I've seen the graphics are not good enough to be noticeably better than games that do support shader 2, especially the way textures get much blurrier when not viewed at close range.
WTF does this have to do with Hellgate?
Anyway the game has an offline mode, jsut like Diablo. If you pay the 10USD a month you get continual content updates like any other MMORPG, they specifically mention CoX as a model. The online version sounds to me exactly like Guild Wars or DDO, with city like hubs where players congregate and the rest is all instanced.