Yeah the alchemy system is in dire need of an overhaul. To me the perfect alchemy system would be something more akin to the Witcher 1, where you have to actually meditate in order to perform alchemy. Each section of alchemy - potions, bombs, and oils would have their own little animations in the background (kind of like skyrims crafting systems) showing Geralt with a mortar and pestle, and heating flasks over a fire for instance. You could then drink the potion either whilst meditating (like in Witcher 2) in order to gain a more powerful affect (and maybe it lasts longer too), which would be perfect for the Witcher contracts where you actually find out before hand what your hunting, or schoff potions down anytime like in Witcher 1 for those encounters when exploring the countryside (this would require a drinking animation, so you have to time it carefully if your already in combat).
I also don't like the incredibly short durations of potions. In the Witcher 1, potions lasted for a couple of ingame HOURS, which is far more realistic. When you drink coffee, the caffeine hit doesn't last for only 40 seconds. You feel the affects for hours afterwards. Obviously if the potions last longer then some of the effects will need to tuned down for the sake of balance; for instance Swallow would need to regen health at a slower rate so as not to become overpowered.
Also, I hate the fact that meditating no longer has its own animation and screen like in Witcher 1 and 2, I also hate the fact that you can do it anywhere, without needing to use a campfire. I've spotted heaps of small campfires all over the map that would have been perfect for this, and it almost seems like thats what they were originally there for. I don't think I've even used meditation once yet, and I've already played the game for 10 hours. At the moment, the only real purpose behind meditating is to pass the time, which is NOT how it should be.
I believe this system would maximize immersion and enjoyment for the alchemy system, and add some much needed depth to meditating, as the current system just feels empty and lifeless in comparison to the previous games.