Let me preface this by saying, I have yet to play the orginal DE, am just about to install it. That being said, I am stateing why I find HR cool, and why, even with it being a "Series" game, I feel that everyone who likes the type of game it is should give it a go...
To me, HR had a nice, interesting story, and even with the choices, I always found myself playing my style of character... A inspector gadget/terminator/robocop mix... Sneak arround till I messed up, anilalte any and everyone, always get the bad guy. It offers a lot of choices, and points you to those choices as well, right from the "first" mission. The first true mission you go on, you ride a helecoptor to the site and your boss asks how you want to handle it. Depending on your awnser, you recive one of 4 wepons, a tranq rifle, a stun gun (slightly ranged tazer), a combat rifle, and a pistol. Then, as you near the entrance, one of the characters tells you that you may be able to avoid the crowd of people by the door by looking at the roof. Yes, the health regen is a little silly, but it doesn't heal you to "full" health, only 100 points, (out of 200). Latter, as you unlock augs, you can burst through walls, leap up to three feet, fall as far as you want... and with the way the game looks, It feels satasfying... especially the first time you punch through a wall and knock out someone standing on the other side... made even more special when you didn't know they were there... Or the nice fuzzy feeling you get when you sneak past the soilders, turrets, and bots, hack the console, turn the machines against the soilders, and walk out a ghost... It's a rediculous challange on give me dues ex mode (Three shots and your dead most of the time), and even has some funny dialouge (There's a robocop referance if you can catch it... Most people don't cuse it requires non-hostile police in the prisinct) plus, the dialouge challanges are intersting, because even if you blow them, the game continues...
And now, for something completely diffrent. The game does have some short-comings. Adam, your character, never modulates his voice. He always sounds gruff and angry. While this can be explained by his augs, it's still wrong. The ending boss fight isn't really explained in game, and the mechanics for it are a little confusing if you don't hack into and read every email, which, by this point, there's more than 200 unique emails in the game. The game gives you upgrades to your augs like candy, makeing it a little too easy at the endgame. The bosses up to the last two are rediculosly easy even on hard diffuculty once you realize they are not emp shielded, (Like you can be, another issue, that while cool, allows you to make a COD style char...)
All in all, if your afraid of hateing the game, or being let down by it, realize one thing. It's a game, that even though it has a link to the orginal DE in both title and set up/game play, It should stand on it's own. Yes, compareing games is a good thing, yes, sometimes games legitimatly suck on their own or when compared to others... (Rogue Warrior for me due to it crashing every 5 to 10 minutes, and no way to fix it, although BRINK is close up there... (Shoddy AI, Built arround co-op, objectives hard to complete... and yet, it sounded so nice... parkour/free running like assassin's creed, gunplay like COD, and classes like TF2...)) But this is a game that should be wieghed on it's own merits...