The Witcher 2 now being my favorite RPG of all time, it's very easy to say that they should stick with what they're doing in enhance it. I, for one, really liked the combat changes. I look back at some of the alpha footage and realize how silly the game would have been with combat from The Witcher 1. Everything about the combat, I feel, was improved in this game. Geralt may have moved a bit slower, but he was much more agile and required darting around like the lore actually suggests.
Some others also really want a lot of side quests, and I'm not at all for that just for the fluff. TW1 really sidestepped the entire character of the story with a lot of pointless derisions which eventually led you to Salamandra. Every side quest in TW2 related to something, like conflict or things that would later rear their ugly head. The side quests should be a lot more intelligently designed rather than being far too plentiful and drag out the game. TW2 may have not had enough content for some, but I'd rather a nice slice than one spread too thin. All the things Geralt did in TW2 made sense for who he was, rather than being usual hero quests.
I feel TW2 also kicks off the real story we're going to see developed throughout the future games with the Emperor's attack to the North. I really like the choices available in this game because they have mountains of possible weight, rather than in other games were literally all that changes are names. I would like a few of these resolved in TW3, but I would also like to see mountains more of these come and twist the story into a winding web that will ultimately affect the fate of the kingdoms.
Some of the RPG elements could use poilshing, I must admit. Again, TW isn't like average RPG games (I think loot in these games is the absolute lowest priority and should stay that way) but the skill system could use a bit more polish. Perhaps give incentive to mix up trees in order to better certain playstyles, give alchemy and utilizing tech as two separate trees, make levelling up more of a big deal, and balance the economy better. I literally spent money willy-nilly.
The boss fights probably need the most improvement. What I really like is that the drauger has no definite strategy. You can try a lot more on him than you can on the Kayran or the dragon. The Kayran had an obvious strategy, the drauger was really dynamic, and the dragon was just really repetitious. Create open areas and more varied fights like the drauger and you will have some of the most memorable boss fights of any RPG. You have an amazing combat system here, so utilizing the real-time strength of it is paramount.
All in all, I can't wait for TW3. Everything's seeming rather bright for CDPR's future because of the great ideas that they have. If they can carry the philosophies they've created thus far into every part of the game (character, environment, effect) then TW3 might just trump TW2.