While I enjoyed TW2's combat immensely, I do believe signs need some tweaking to make them balanced.
I've played the game twice and the only sign I really needed was quen. I think Quen is too overpowered in TW2 while Aard and igni have been toned down, especially Aard.
I can't figure out whey they did away with disarm power of Aard. Disarming the enemies would come really handy when fighting a group of enemies (which Geralt does a lot ). I hope they add another skill slot for disarming using aard ( like they have two slots for yrden, quen and axii) in future patches or EE.
Also can't understand the rationle of putting Igni so high in the skill tree. It's basic sign, should be with quen or aard below.
Though I like how they changed yrden, much more useful now.

I'm playing on normal but I'm actually using Aard more than Quen. Sometimes for hard fights I just enable Quen in case I'm careless. However for most fights my Aard tends to stun an enemy about 60% of the time, and then I just do a fast leaping attack followed by a strong attack and another fast attack, then I roll away and repeat. Since most of the time I avoid attacks, I tend to save my vigor for Aard. Though when my max vigor increases I can probably afford to use Quen in conjunction as well.

Igni seems okay for killing weak enemies from a range but then you could just use throwing knives. Though I haven't leveled any skills outside of my alchemy tree yet. Yrden is good and I use it sparingly but most of the time I just use Aard since its quicker and more efficient.

Igni is monstrously good if developed well.

With burning and area effect, plus all sign intensity upgrades you can pretty much kill, or weaken, lots of stuff at range.

I guess it's late in the tree to reward those that specialize in magic (like me in my last playthrough).


P.S.
I never really got good use of Aaard. Usually, effect lasts too short, for me to be able to exploit it. Just time needed to come close to enemy that Aard pushed back is enough for enemy to recover, and take guard stance.

In fact, I started using Yrden as way to stun opponents. Seems more effective then Aard. At least with no upgrades present.

IMO Quen should be removed or be same as in TW1 , once you attack shield disappears.

i dont think Quen should be removed, but yes it sohuld be made the wat it was in TW1, maybe with the additonal ability to deflect to multiple enemies. rt now its just feels way too over powered.