Focusing on one path also makes you very strong. On normal difficulty I went on the swordsman path and only later in the game upgraded to level 2 Quen. I used bombs only when fighting the elves in Act 1 and potions only in the Kayran fight. I didn't use traps at all.

The point is to upgrade the skills that fit the fighting style you use. And this can be anything between a single path and a combination of all three.

But many times it is a good idea to use even the abilities that you have at basic levels. :)

Sure, you can put all your points into one path and they will make you pretty strong, but you can't get through the game just using that one aspect. I just got done doing a playthrough where I only put points into the swordsmanship tree but there were quite a few situations where I couldn't get by just using my swords.

This. All I ever invest in is the Swordsman path and I never had any problems. Once you get whirl and group finishers, you're practically unbeatable. I always felt like bombs and traps slowed me down, heh, but that's just my gaming preference.

I prefer the jack of all trades approach. It seems closer to the spirit of the books. Witchers are not tanks or spell cannons. Usually I have a primary and a secondary skill set. Focusing on magic is fun but since the monsters will get all up in your face, you will need some weapon skills to deal with that. And being a swordsman is cool but magic & alchemy are helpful before the monsters get all up in your face.

Remember that combat in this game is more tactical than TW1. If you know the ground, spread some traps around first. Keep a mix of monster specific blade oils handy. If you have time before a fight, pick your potion intake carefully. Stock up on bombs & daggers.

Keep at it, it takes a little while to get the right mindset. The game provides you with all you'll need: weapons & armor, bombs, potions, skills.

In the words of Big Daddy: "Tool up Honey Bunny. Its time to get bad guys."

Um... I felt that heliotrope sign was useful, but with those "group" finishers, I have to do something wrong, because my "groups" only ever consist of ONE enemy and that I can do more effectifely by stunning or freezing. I have to get sooo many hits in, to finally get the finisher and most of the times, there's no one left to finish off, once the adrenaline bar is full (with 709% adrenaline generation!!). If there is a big enough group and some enemies are left, I still only kill one of them. Wasted talents, won't do swordsman path again. Only time it was useful was in the mist, after filling up the bar by hitting wraiths and offing a draugir with the finisher (but the second time I tried that, I killed a random soldier ghost instead of the draugir).

And I think bombs are way useful against groups, especially if you're still weak, need to keep them at a distance - and dancing star into some harpies is just fun. :D
Oils on silver swords don't work (hope they patch it with 1.3) and daggers did no damage for me, not nearly as much as bombs. Other than that, I enjoy using all tactics that are available.

Eh, I like group finishers, but only in combination with heliotrope.
As in, activating adrenaline casts the heliotrope after the execution animations happen ..

It's really silly due to regenerating at least 3 points of vigor during the animation .. usually enough to spam up the adrenaline bar well before heliotrope runs out.

Although, there's usually nowhere near enough foes to use all that juice on .. but it does make assaulting the nilfgaardian camp hilarious.

I think I saw somewhere that group finishers only finish off one non-human enemy, whereas if you use it against humans, you will finish off 3 opponents. Might be a design oversight.
I specialized in Alchemy once (with points in Foot Work and Position though, but no points elsewhere) and it got me through everywhere. There is one part that is tricky for non-swordsmanship build, but anyone can pass it with prudent use of basic signs.

This is true except for magic build.
1. There is no +vigor regen skills in magic tree itself.
2. So unless you get an armor with decent +vigor regen, invest in Schemer under Swordsmanship, invest in Catalysis under Alchemy, your vigor regen is generally pretty low.
3. I find that there is a pause (~ 1 second) before I can cast signs after dodge-rolling.
4. There is a 2.5-3 second timer before your vigor start to regen after you cast a sign.
5. Your damage per second is pretty low until you hoard equipment with +sign damage and invest in all +sign damage skill.
6. Quen II is nice and all, but if you are relying on signs for your main damage output, you get crippled by the zero vigor regen.
7. A lot of the perks you get from the skills are not stackable, unlike the many passive bonuses you get on Alchemy and Swordsmanship.

Putting all that aside, the strongest builds are the hybrids, but building your character by focusing on a single path first is very advantageous.

If it's a stronger enemy (draugir, for example), you can only kill one at a time. If it's a weaker enemy then you can kill up to 3.

How do you define stronger though? What happens if you apply it onto harpies and gargoyles?

I admit I don't have a real definition of 'stronger' - um, they take more hits than usual to kill? If I remember correctly, I was able to kill 3 harpies at once. Don't remember about gargoyles, I'll go check it out right away.

EDIT: One gargoyle only.

Yeah, these buggers burn a whole lot faster than anything else. And even if they swarm me as a group, no more than one gets finished off, while you get into trouble with the others, because the animation has to play out, before you can tend to them.

What does berserk do, anyway?

It doesn't have to do with enemy strength as far as I can tell. It's a sentient creature/monster difference. From my time using group finishers you can finish up to 3 humans/elves at once or one monster with each finisher.

I just have to drop by hear and say that I truly dislike the group finisher in the swordsman tree. I hate the finishers already, but adding a sort of godlike mode where you can perform it at will (on up to three enemies at once, to that), is just ridiculous. Not only is it incredibly unbalanced in a challenge point of view, it's also unattractive and plain ugly as a game mechanic. The first time I got this was during my second playthrough, and without mods, you build up adrenaline insanely fast. I quickly noticed how easy it was to exploit, as well - I got it ready while fighting some regular enemies, and then a group of three stronger enemies entered the fray; I just hit X and they all died immediately. Heliotrope is fine - in vanilla, the duration is too long, though - and I haven't tried Berserk yet; but the Group Finisher move is an example of truly questionable game design. I refuse to use it ever since I found out what it does, after that second playthrough.

For anyone coming into this game and expecting a fight system like Batman:Arkham Asylum for example , the Witcher 2 system can be a huge shock. Most combat systems i have played are quite fluid and very responsive, and so when you first play TW2 it can take a while to get used to its unique style.

TW2 combat while good, isnt perfect. It does have many problems imo with bad targetting and blocking being pretty useless until you invest plenty of points into reducing the vigor taken for each block.
Geralt can feel ponderous at times too, and that unresponsive feel when you seem to have to wait a second after an action before you can use a sign or bomb.

But when you get used to it, it can be fun. But you have to work at it, it isnt easy to get into the combat, but it can be rewarding after a lot of practise. But that doesnt make it perfect.