Nowhere near as good as the original, but still a superb game on its own merits and arguably the best 360 launch game.
Hell yes. But that's not to say I wasn't disappinted with it. It's biggest problem is that it's not faithful enough to the original Perfect Dark which I'll explain in the next three paragraphs.
Problem One - The weapon selection in Perfect Dark is and was the best assortment of weapons ever in a game. There were tons of them, all of them useful in different situations. If they had just ported these over with better graphics, that would've been fine. But instead, they've only got seven weapons from the original game.
Problem Two - The voice acting is awful. Perfect Dark was one of the only N64 games with full voice acting, and it was acutally surprisingly good. But now it sounds like teenagers on their first run-through of the script. The emphasis on the foreign accents are so suspect it's annoying -- Carrington in the original game was a believable Scottish dude, but now he speaks stereotypically saying things like 'wee' in his sentences. And how Joanna Dark suddenly changed her American accent in this game to her English in the original in just three years is remarkable.
Problem Three - Some excellent multiplayer features in the original PD have been dropped. Gone is the awesome Counter-Operative mode (but they say it'll be a available in an update), gone are the thousands of character head and body combinations (you now get just SIX non-customisable skins), gone is the wide assortments of simulants with personalities (though an update adds a few of these personalities back), and gone are the classic maps (with the exception of Facility and Temple, thanks to an update).
So, now let's get onto the good stuff in Perfect Dark Zero.
The weapons are among the most realistic-looking ever in a game. They are also very balanced and most fun to use. Yes, despite the fact that lots of the originals have gone, that'll only bother fans of the original PD, so anyone new to the series will encounter among the best weapon selections ever.
The sound is great. The voice acting sucks, as mentioned, but the music is superb and really makes you feel like you want to kill something. The stomping guitars are so cool. It's worth saying that the theme tune is different to that of the original, and you only hear the original very briefly during the last cutscene. But in general, the music was much more memorable in the original PD than it is here. But the guns sound awesome and the atmosphere is great.
It's superbly fun to play. This is the definition of gameplay over story or presentation. The original PD was a game that made you good or made you dead. The same is here. The single-player does demand some trial-and-error and memorisation of enemy placements, but in the end it just makes you better at the game. If you play the game on Agent difficulty, it's a simple game. Secret Agent is more of a challenge, and Perfect Agent is only for the true Gods of the game. Dark Agent is for the few elusive people who are probably better at the game than Rare themselves.
The multiplayer is fantastic. Team Killcount is the best Deathmatch varient online or offline, but made even better with the Psychosis Gun -- If someone plugs you with the secondary fire, you will see team-mates as enemies, and as long as friendly fire is on, there can be some laughs. The Dark-Ops varients are also lots of fun, with Infection being the best online mode and Eradication being the best offline mode. Eradication is essentially PDZ's version of Counter-Strike... no wonder it's so fun! There are only six maps to begin with however. Updates bring it to a grand total of 12, and playing on Facility gives some awesome nostalgia. Hopefully they'll soon add classics like Complex and Grid.
All in all, the game is superb. It doesn't do the original game perfect justice but judging purely on its own merits and not of the original game, it's one of the best first-person shooters in a long time.