The first Deus Ex was highly acclaimed by players and critics, winning many Game of the Year awards in 2000. I recently played it for a few hours trying to reignite the feelings I had for it 3 years ago. Unfortunately, the game hasn't aged greatly. It still has some good things and I can see why I loved it so much.. but for the most part I'm very bored by it now. The story progresses too slowly, the levels are too wide open and plain. My biggest gripe is the general uncertainty of what I need to do now to leave options open later in the game. For example, in one level you may use a couple lock picks unlocking a container that contains something you really want. Then when you arrive at the next level, you discover that you need two more lock picks to open an alternate path through the level. Unfortunately you only have one left. You never know when you should or shouldn't use your lock picks. Some might say this adds a certain amount of strategy to the game, but I think it's more of a gamble than strategy. If you know you'll need 2 lock picks in the next level to do what you want, then sure it would be strategy to not use any lock picks in the current level. But when you don't know, you can't strategize. The lock picks are not the only case of this happening.. it's a problem with almost all of the game's RPG elements. Using multitools and choosing skills suffer from the same problem. With the skill system it was a matter of making a choice about what area I want to specialize in before knowing which ones would be most useful. So maybe in the first level there was a part where sniping would be good, so I use skill points on that. Then on the second level there is no sniping to do, so now I've got a useless skill.
But enough complaining, the game does do some things right. The story, when you finally get to the end and condense it all in your head, is actually pretty good. And the main attraction of the game, being able to solve a problem multiple ways, will probably never get old. All in all, the annoyances I have with this game are too major for me to ignore and I usually just end up frustrated, bored, and/or confused.
Now, more than 3 years later, Deus Ex: Invisible War arrives. They released a demo a couple weeks before the game came out, and the reaction from 90% of people seemed to be "this sucks." And well, the demo did kinda suck. The level was completely changed from the version of that level in the game, it was a fraction of the size and major things were moved around. So you don't really get the feeling of the game from it.. you just see the crappy things (most of which were already fixed in an official patch to the full game). Just do yourself a favor and forget about that demo completely. Hopefully they'll release an updated demo so you don't have to buy the game to see if you like it.
I played the game before applying the patch for about 30 minutes.. and well.. just make sure you patch it before forming an opinion of it. The patch improves almost everything that annoyed me. Now that I got that out of the way..
Invisible War eliminates the problems I had with the first Deus Ex. The story and the game in general moves forward a lot more quickly. The levels are tighter and more detailed. I've heard some people complain that the levels are too small. I'd definitely disagree with that. They're not really small at all, there's just less wide open empty space. It's like comparing a piece of cake and a brownie. The cake takes up more space, but most if it is just air.
There's an even greater sense of being in control. Various organizations and corporations are using you to carry out their plans, you can choose who you want to help and who you want to snub. So far I haven't run into a situation where I wasn't given a choice about what I wanted to do. And of course there are still many options when it comes to getting past an area/obstacle.
The skills system and lock picks from Deus Ex 1 have been eliminated (multitools now perform the function of lock picks as well as their original function). Multitools are plentiful enough that you don't really need to worry about using too many, you can always find more (I've still got 14 multitools in my inventory and I've been using them every chance I get).
Biomods are sort of similar to the skill system, but you don't have to worry about choosing one that won't help you. Every one can give you an advantage, it just depends on how you want to play the game. It never felt like I made a wrong decision, unlike Deus Ex 1's skill system. There are 5 upgradeable biomod slots, and each one has 3 areas. You can only choose one area per slot. Upgrades come a lot more often, so even if you change your mind you can usually afford to start from scratch with a new upgrade area.

Caption: You may wonder what this picture has to do with anything. I don't need to explain myself to you.
I'm having trouble thinking of things I don't like about the game, which I suppose is a good sign. It doesn't run real smoothly.. I guess that's one purpose the current demo can serve, you can see if the game even runs on your system. The NPCs(non-player characters) sometimes act goofy, and only one person can be talking at a time. The combat AI isn't terribly bright.. they'll basically just run into a room I'm hiding in while I stand in the corner and mow them down with headshots from my pistol. But the game isn't really about combat, so I don't mind. In Deus Ex 1 stealth seemed to be the preferred method to play the game, but in Invisible War it seems to be much more difficult and something you decide you want to try for fun since you can easily take down just about anything.
I like this game a lot. I think it's much better than Deus Ex 1.
12/20/03 UPDATE
I finished the game. Thought of some more things to say.
The graphics in the game are, at the very least, consistent. I can easily believe that every location I visited is in the same world. The shadows are pretty cool. For example, if you knock over a lamp it casts realistic light and shadows. I believe this is one of the first few games to do that. Previously lighting in games would be static. If you could knock over a lamp at all, the light in the room wouldn't change.
Some of the textures aren't very crisp or high resolution, but I didn't notice until someone pointed it out to me. I guess I just don't care that much about pretty graphics. I'm more interested in if the graphics' style fits the game, which it does in this case.
One thing the game is lacking that the first Deus Ex did well is having memorable characters. Most of the characters in this game are boring/generic people and you don't really care if they live or die or you never hear from them again. There's not really any funny one-liners (like Gunther Hermann's lemon-lime from the first game), the game could benefit from a little more humor in general. Yes we're dealing with the fate of the world, but that doesn't mean we can't laugh a little.
It took me about 15 hours to complete the game(and I plan to play through at least a couple more times, to make different choices in the plot, there are multiple endings). Some people said they beat it in less than 10 their first time through. And if you're trying, it is easy to beat the game quickly. But this is the kind of game where you get out as much as you put in. If you explore the game thoroughly you'll probably enjoy it a lot more as well as make it last longer. Games are supposed to be an interactive form of entertainment, and Invisible War is a great reminder of that.
01/08/2004 UPDATE
Well, I never did end up playing through the game again. I started to, but the second time through--the good things I had already seen, so I started focusing on the bad things. So, that kinda made me want to stop. I think I'll eventually go back to it, as I do with any game I liked the first time I played it.
NOTE: I may update this review again in the future after I play through the game again or think of more things to add.