I played the first Hitman when i was around 7-8 didn't know English very well at the time so i would just kill everyone and hopefully pass a mission.

I actually started with Hitman 2 on the Gamecube but I never got in to it. Later on I bought Hitman 2 on the Xbox and I fell in love with the game, there was just something about every plan coming together and knowing that the execution was coming closer and closer that I found to be fun. I continued with Hitman Contracts which was definitely my least favorite although I still loved it. 
 
Then came Hitman Blood Money, and I thought that was absolute perfection. I replayed level after level just to see the different ways of completing it. I unlocked every gun modification and after wards I went back for the Silent Assassin rating. 
 
I played Hitman Codename 47 after every other entry, and I actually enjoyed it a whole lot. That restaurant level where you could pop out of the restroom and just shoot the targets down was incredibly fun. 
 
 The Splinter Cell and Hitman games would always be the games I would go back to over and over, I still go back to them right now actually. I do hope that the new Hitman entry at least has a bit of focus on stealth and planning, because the newest Splinter Cell games focused on action more than anything else.

It was the first time i saw ragdoll physics!

I also just started revisiting Hitman. Bought the Ultimate Contract box, which contains all games on one DVD. 
I got as far as the "Say Hello..." mission before I went on to play Hitman 2. The focus on shooting up the place is just not what I like Hitman for, and it seems I remember the first game being more stealthy than it really is. What is funny is that I am certain I managed to beat that mission when I was younger without really killing that many people. I remember getting an outfit that allowed me to walk around with the sniper found in one tower, then sniping the bastard from outside through the window. But that just doesn't work for me now. 
 
The first game is good, and I like the story really. But revisiting it now makes me think it is the weakest in the series. Having a rating, and having a focus on only killing your target, makes the later games a lot more fun. 
 
For the next game, I hope they stick to the stealth and planning as they have in the latest games. If it is possible to beat every level without killing anyone but your target, then I am happy. If you cannot do that the first time, but later once you have unlocked more weapons for your customizable safe house, then I am even happier. I love unlocking shit.   
 
Also, I want the slow motion button from Codename 47 back. That is so much fun to play with.

Hitman is a series that appeals to me in concept more than anything else. I've never played a single one, and have occasionally toyed with doing so, but then I remember that even though I'm not nearly as violently opposed to stealth games as some other people, I'm also not very good at them. Never finished Thief, and the way I played Metal Gear Solid consisted of "Shoot everyone in the head with a tranq dart" Which worked for the most part.

I've only played Blood Money so I can't comment on the others, but if it's a good indication of what the rest of the games is like, they can't be very good. 
 
I actually loved Blood Money at first, and seriously expected it to end up as one of my very favorite games of all time. A couple of missions in, however, it went downhill. While there were light action elements, it was more than anything a puzzle game, and what puzzle games need are variation -- unlike a reflex-based challenge, a puzzle stops being challenging when you've overcome it once (unless you forget how to solve it, but than can take years). Blood Money had no variation. While the environments changed (and were all amazing -- serious props to the artists), every mission basically boiled down to the following:

1. Find a guy with an outfit that lets you go to more places. Wait until no one sees and kill him.
2. Go to the places you couldn't before.
3. Find a guy with an outfit that lets you go to even more places. Wait until no one sees and kill him.
4. Go to the places you couldn't before.
5. Find your target and kill him.

" It was the first time i saw ragdoll physics! "

I had Hitman for my Gamecube, and I didn't get very far. I was pretty good at Thief, always taking the highest difficulty level and loving the challenge, but for some reason I never quite fell into the mode Hitman wanted from me. Maybe I needed to take more time on missions, but I soon found myself playing other things. I probably would have enjoyed it, especially for the added challenge of not killing indiscriminately, if I'd spent more time with it.