I've recently employed Unchained into my games and I must say that Consolidated vs Grouped gave us the biggest fuss. Note that in the games that I run/play every player at the table is also a DM*, so every rule change or book inclusion must be agreed upon, preferably unanimously. So for us, Unchained brought up a lot of really awesome things that each of us could see using for different reasons. Here's a basic overview of our reactions and decisions.
*(Each player DMs for a campaign as the other DMs find good plot hooks in the current campaign to link in their own campaign for their next turn as DM.)
TLDR version: Background Skills only OR Background Skills + Skill Groups OR Background Skills + Skill Groups + Consolidated Skills + Advil
Background Skills:
Background Skills rock; use them.
Consolidated Skills:
Consolidated Skills are interesting in the manner that, at face value, they 'simplify' skill use in-game. However, the cost for that is changing virtually everything. Every feat that works on a skill; change it(our particular example was Fearsome + Intimidating Prowess). Every race that gets a bonus; change it. Every magic item that offers a bonus to a skill; change it. Making custom races involves a bit of additional thought, especially if you want to make it work for both with & without Consolidated Skills. Then there's the common trait that, when you level, there are some skills that you rank up every single level. With Consolidated Skills, this can effectively prevent you from gathering new skills.
Now, of course, many of these issues can be resolved simply by saying that it works a little differently; i.e. Fearsome + Intimidating Prowess works easily by modifying Influence when used for intimidation. However, this eventually requires the DM(and/or players) to commit every situation to memory for immediate recall or some such nonsense. I have no time for this; that's why I have a character sheet*. I have a difficult enough time remembering that I get a bonus vs fear effects or whatever. I cannot reliably apply every single rule caveat as a result of adding Consolidated Skills.
*(note: sheet, or two, not booklet; printer ink/toner can be expensive)
Skill Groups:
Skill Groups adds skill aggregation while still permitting you to really focus on one particular area. Best of all, you don't have to change the meaning of a bunch of skills, feats, magic items, arbitrary spells, racial abilities, ..., etc. What's more, DMs don't have to remember or change the way they DM. "Roll Diplomacy." "You mean Influence?" "No, I mean Diplomacy because there it is, on your character sheet."
I also feel like I can do more with Skill Groups. My character may decide to be well-versed in religious matters. Perhaps he's taken Lore(Lamashtu) and specializes in Knowledge(Religion) & Knowledge(Dungeoneering). Yes, Skill Groups gives me the option to effectively train in ALL skills through the Scholarly group but I don't have to limit myself; my Monk can take the Perceptive group and specialize in the individual skills as desired. I just couldn't find a good way to do that with Consolidated.
Another aspect of Skill Groups that is useful is the fact that our group no longer has to spend excessive time(more than 5 minutes) deciding what to do with skills as part of leveling up. All specialized skills are 'done'; we don't have to put any extra points in them or decide not to max out Perception in order to bring up Spellcraft. Once you specialize in a skill; it's done. Congratulations, you will always have your level(or half of it) applied to that skill + any other pertinent bonuses. The same benefit applies when creating, say, a 12th level character for a new game.
With all of that said, I did find that Consolidated Skills is actually not too bad if combined with Skill Groups. In fact, we've effectively ruled that Consolidated Skills should not be used without Skill Groups. The reason for this is that you can specialize in specific aggregates that Consolidated Skills provides and you no longer have to worry about putting points into them. This, effectively, makes it tons more useful and really brings out the flavor in a character build. Now my Inquisitor(Spellkiller Inquisition) can pick up a group that he's trained in(using just 1 skill group) and specialize in the other areas as time goes by. Also, additional specializations are available every level if you take +1 Skill Point for a favored class bonus so you don't need to feel too limited by combining both of them. Although this feels like Skill Groups 'fixes' Consolidated Skills, remember that you still have to contend with all the skill description changes, feats, magic items, ad infinitum, ad noying.
So, that's my buck-fifty on it. I hope it helps.
