Sign casting
I just found out that right after dodge-rolling, Geralt is unable to cast signs at all for one second or so. This happens regardless of whether he stops or runs after dodge-rolling. Even holding Q do not yield any response. On the other hand, attacking and throwing bombs seem to work fine right after dodge-rolling though.
- Does anyone have this issue?

Blocking/Dodging
After some testing (see video here http://www.youtube.com/watch?v=2G6bZdFYHqg), I found out that blocking is very slow after getting hit once whereas dodging was much faster. But in the case of getting blocked by an enemy, blocking is much more effective than dodging.
- Is this an intended design? Seems weird to me.

Triggering the Witcher medallion
In short, when you are in the transition between moving and stopping, holding the Z button does not do anything. But that only happens when you are unarmed. It works fine when you are armed. See video here: http://www.youtube.com/watch?v=vD74r_B-S0g
- Anyone else experience this?

Yep. And they are presumably working on fixing it.

I just use Q. I never really noticed the sign issue before because I usually just press Q multiple times and it fires up on one of the subsequent presses. But if you just press Q once or hold Q down right after rolling nothing happens. I can easily replicate this.

I can't say I've run into it, but a lot of people (yourself included) have, so I don't doubt it exists.

Personally I DID notice quite some input problems.

One would be the mentioned delay in activating block in certain situations and the second (maybe not necessarily related with input but still) the step forward Geralt makes instead of actually performing the base attack on left mouse click (default setting).

And no, the step forward issue is NOT related to enemy distance. It occurs even when I swing the sword with no enemies around.

Hoping this/these (among others mentioned) will get a fix. :)

Yup.

These are some of the issues that annoy me greatly about the game. Unresponsive combat which can get you killed.

Getting fixed soon hopefully.

Yep.

Casting signs is my biggest peeve. I have to stop, wait a second, then cast the sign. Especially annoying when casting early quen, as it gives enemies time to reach you and whack you, taking half the quen away. It's always cast-n-roll for me.

Blocking, I don't even bother... I just roll or take the blow.

Hehe, yea! Forgot about this. It was/is quite annoying to always have that 1 second gap before being able to use a certain ability or sign.

As a matter of fact, I even stopped playing the game due to several reasons (F5 quick save crash to desktop bug, input problems, Win7 mouse lag). Hoping that patch 1.3 will save me. :)

Never had the medallion issue, but the sign controls and block periodically go on a furlough in the middle of a fight. The problem goes away after you dodge/roll or get hit. I guess it taught me to dodge/roll a lot.

And every so often in longer fights (like the Melitele's Heart one) the roll controls also go on the furlough, and instead of rolling, Geralt just runs. Also sucks.

I have the casting problem using Q key, usiually have to double click it.

For rolling I typically have to press space bar multiple times. Unlike blocking, if I hold down space bar my keypress is ignored (after getting hit or blocked).
Does it happen when Geralt is running / standing still? I find that when Geralt is running / standing still, holding down the Q key would make him cast the spell although sometimes not straightaway.

But for 1 second or so after rolling, I find that Geralt does not respond to Q key even if I hold it down.

This is the big problem with the combat. You get used to it and the combat is otherwise really fun, but it should be fixed.