There is much talk about speed, controls and all that has changed or will change with RTW in the light of the recent demo. Hopefully, the full game will silence most of our speculation :)

For one, I don't live in the nostalgia of STW (I have not played it) or MTW; I like MTW a lot, and I quickly moved away from SP to MP (I did not like the campaign much).

I'll focus on MP, so pause and mods are not potential alternatives, it just won't happen. Same for speed bar; it's not enabled in MTW MP, and I don't think it will in RTW MP (I'd liked to be proven wrong though).

MTW MP is very rewarding and nice to play, a very good experience on the long run, but suffers from a very difficult learning curve.
For good strategy games, we often say they are easy to learn and tough to master; MTW is not easy to learn.
I think one of the main reason the game failed to attract large numbers in MP was that the inital battles in MTW MP were not a good experience, more of a frustrating, lost-in-control-no-pause-mayhem-experience*. Beginners were often not able to move their army correctly, not so much because of lack of tactic skill, but because the game was already too fast, and their mastery of the interface inadequate. Most know what to do, but the game stands in the way.
And I'd not blame that on the beginners; if the game interface is not good enough for generals to move armies according to their wishes, I'd blame the game, not the general.
I mention pause as no solution before; let's put it that way; for me, every time someone got to use pause for a game reason (you can loo all you want :) ), that means CA failed to deliver an interface easy enough, and a speed adequate enough for the game to be played.

With the demo there is hope for a better interface, but the faster speed will make it even tougher for SPer or player playing other games to move their army as they want in RTW. So the learning curve might stay just as steep. Not much of an improvement for people new to MP.

For MTW veterans, those with thousand of battle in STW, I can only guess (I'm a MTW noob :p) what other issue they might face.
MTW MP has appealed to a different crowd from RTS players, probably because it was very tough to learn (see above), and also because the game was different, with a heavy focus on morale and tactics. A lot of the game enjoyment came from the possibility to have deeply tactic and wellthought battle. Chess like, but in realt time with some action. At least for me :)
Even that part of MTW MP was not perfect, and there is a lot to say about the imbalance of the Rock Paper Scissor system** that made the game a little less tactically rich than it ought to be, but still enjoyable, and that's another story anyway.
To have interesting tactics, we need the possibility to have action and reaction, to commit reserve, to help an ally...
Game speed will influence that. And so will the interface.

Let's take a classical example; one ally being attacked by two ennemies, and we'll assume we want to help our ally.
1st, I need to be aware my ally is attacked; that means a good camera system and an helpfull minimap. Not sure anything has changed positively in that respect. So the 'awareness time' is likely to remain unchanged.
2nd, I need to order my units to move to my ally side. Better control can help. Then the units go to do the walking. And that's faster for me thanks to higher speed, on the other hand attacking armies are also faster.

I need to do that before the two ennemies get to my ally army. I move faster, but they move faster too. And they move first. If we assume the first step time is constant, faster speed means my ally will be in a double situation for a longer time.

Other example; retreat tactics or refused flanks will also be tougher to implement; if attackers move so fast that the defenders don't have the time to react by moving back, then moving back possibilities will disappear. Again to retreat you need to be 1/ aware of the attack, 2/ actually move back. Once moving back, as both armies are faster, it's not an issue, but if the game is really fast, I doubt a defender will have the time to order a proper retreat before the attacked make contact; it's already difficult in MTW, speed will make it tougher in RTW.

Faster speed help the first mover, and makes the action/ reaction game much tougher. There will be action, but not much of a reaction.

Now, to be fair, speed in only one part of the problem. If RTW comes with a really great camera/ minimap system, or with a very easy to way to implement teamtalk (pressing t or y in game was not really great), maybe the reaction time will be shortened and that will help to have action and reaction.
Also, other factors can help to make the game slower without changing its speed.
Let's go back to the first example; one ally being attacked by two opponents. One of the factor is morale; if outnumbering morale penalty are low, maybe our ally can survive a longer time, and we can come to help. Even in MTW this would play out very differently in different setting. When playing at very low florin, with low morale, two attackers on one defender was often a very fast defender rout; outnumbering penalty were too big to manage at low morale.
At high morale, it was quite doable to hold a loooooong time at one defender.

But now we are playing with other variables, such as morale and morale penalties... that might affect the unit behavior in very different ways...

At the very worse, the first movers advantage with higher speed will be such that in MP we'll only see rush and double rush. Counter rush will be tougher. No more tactics, no thanks.

Slightly better, but still not a good situation, with more training and time spent on learning the camera and interface, there will be room for action and reaction. In that case, I am pretty sure that many won't bother going throught that very tough learning curve and RTW MP will be played by a very small number of players who got it, and dropped by countless others...
A bit like MTW MP today, just with a even harder learning curve thanks to additional speed.
Also, in that situation, skills is not so much a question of sound tactics, but a question of knowing the interface. Hardly the "easy to learn, difficult to master" situation.

At best, we'll get a beautiful game, slightly improved controls, and still a tactically rich game (who knows maybe even better than the poorly balanced MTW MP).

We'll see. That's just Demo speculation :) But I hope it explains a bit the concerns of some MPers regarding speed.

Louis,

*three other reasons; gamespy, and a non intuitive buying system (beginners don't know what army to take), no mp campaign.
** Rock Paper Scissor system; sword beats spear, spear beat cavalry, cavalry beat sword; was broken in MP, and spears were not needed.