I never played Deus EX, I just jumped into HR and loved it. The augs supported a wide preference of gameplay, hacking was fun, stealth was realistic compared to a lot of other games, but I only have one bone to pick with it.
IMO: The Bosses were terrible, in a game where you are rewarded for stealth gameplay, non-lethal disposal of enemies, not triggering off alarms and pretty much staying invisible, with trophies such as "Ghost" and "Smooth operator".
I found myself passing through the level with great stealth, almost never even having to knock guards out, and I prepared my character accordingly, I upgraded the appropriate augs and stocked up on the proper equipment, then found myself in the boss fights facing tanks who insta-kill you and dish out grenades in 3's every 5 seconds.
The first boss was a shock, but fairly easy compared to the other 2, I had almost no ammo and coincidentally had 2 smoke grenades which took him out because he never moved.
The second boss had the typhoon which had me bunny hopping whenever I saw her, and shooting the power stations to electrify the floor, needless to say I didn't have the anti- electricity aug because I never found a need for it. I had to miraculously survive until she clipped into a wall when I started emptying my weapons at her.
[Spoiler Alert] The third boss was the worst, I'd invested in anti-EMP, Anti elec. Anti-concussion augs, I got the see through walls aug to see invisible people, I got the homing bullet upgrade for my combat rifle, My gameplay stayed the same within the levels but now I had to stock up on weaponry and ammo just for the boss fights.
Then wouldn't you know it, they disable my augmentation, and I had to fight an invisible guy, who jumps walls, and has an insta-kill plasma gun, who dishes out all kinds of grenades.
The only way I could beat him was miraculously hiding behind a block, and have him stuck in a loop of jumping over the wall, then jumping back. while I blindfire at him with my homing bullets until he died.
When I look back at games such as God Of War, Metal Gear Solid and others, I don't remember the deaths, I remember the adventure, so in my mind the hero never died, he plowed through the story like an immortal the way it's meant to be told. But in HR, When I look back, I honestly can't remember the levels, I can only remember dying so much in boss fights even though I rarely ever died in the levels.
That plus the face that I mostly had to use in game glitches to beat the bosses, in my head, Adam Jensen never survived.
Kratos is an Indestructible god, Nobody knows what Solid Snake looks like, and Adam Jensen is dead.
That said, The 4th boss fight was brilliant, It utilized everything I learned throughout the game, quick hacking between turret patrols, evading guards, and avoiding/disabling/shooting cameras. Which makes me even sadder because obviously the developers know how to make a good boss sequence, Why didn't they.
**BATMAN: ARKHAM ASYLUM SPOILER ALERT**
Kinda reminds me of that ridiculous Joker on steroids boss fight.