First...everyone can be everything. You have an undead revenant who sold his soul to Baal for revenge and became a half vampire...no problem...he can also be a Paladin.......
I'm not sure what a half-vampire is, but an undead revenant who sold his soul to Baal for revenge doesn't sound LG. Perhaps this character could be a fallen Paladin, but not a Paladin by the rules.
That type of thing sort of turns me off. In the DMG it lists the option to have core races that are limited (DM fiat) to certain classes. Maybe the players won't like it, or maybe they will...but there are actual optionary ideas for which races would qualify or at least favor which classes.
Pathfinder focuses on the core races for players. Even the Advanced Players Guide didn't introduce new player races. However the final decision on allowed races for a game is in the GMs hands. It's not really something that has to be codified in a core rules book.
In addition the favored class idea, where you can have XP penalties negated if you are in a specific class...but if you're race doesn't have it...then you get the full weight of an XP penalty if your classes are too far apart in levels.
It appears that Pathfinder doesn't have these options...which leads to number 2...
I didn't like class level dipping. I take 1 level of fighter...than 1 level of Druid, then 2 levels of Weapon Master...etc.
The Experience Penalty thing isn't in the Pathfinder rules, but the classes now have many more advantages for staying within a single class so players are less likely to dip into many classes. There are no dead class levels like you saw in 3.0/3.5.
The third item was the I want to be a monster syndrome. Everyone could be any monster they want...and of course the townsfolk will respond as if they were normal. Of course that made no sense to me...and I could always stick by the core races in the PHB...with a few optional as listed in the DMG if I wanted. Stats were listed in other books (savage species, MM's later on), but those were really optional, with the Core races being what was considered official and what a DM could use as an optional ruling to back himself up if nothing else.
What or where in Pathfinder does it say Monster PC's are NOT the norm but the odd and rare exception?
I don't exactly see where Pathfinder encourages players to play monsters more than in 3.0/3.5 or 4E. Are you looking for a statement that says "Thou shalt not play anything but races x, y and z"? I don't think that should really be necessary, but the focus in PF is clearly on the core races.
I would say that the player race issue is really more of a campaign setting thing. Let's say someone wanted to use Pathfinder to run a Planescape game. In that case you'd expect some greater leeway as to player races. On the other hand, if the GM wants to run a more standard campaign he'd be entirely in his right to limit the player races to the standard races in the players handbook or even a subset of those.
Multiclassing spellcaster - Point blank, unless you did certain munckin builds...Multiclassing a spellcaster was a good way to hose your character powerwise...I didn't see anything in PF that fixed this.
I'm sure a multiclassed Sorcerer/Wizard will suffer as much as in 3.5 so no change there. However, there's much less reason to multiclass now so hopefully players won't be as tempted to min/min their characters that way.
Bards - Bards were great at being Jacks of all trades...able to do everything...but not good at anything...which meant that overall they could fill a gap...but were ineffective overall at being a good class since...they weren't good at anything (as I just said). They didn't really even have the synergy to have all things work together to make them better then any other class really, in my opinion. Bards got the short end of the stick in 3e (unless you used the Paragon path option in UA, though in that case that was more because they got a Wizards spell casting option...but a better BAB overall, though still a little underpowered in relation to the Wizard...it made for a good mix). What did PF do to actually FIX the bard to have powerlevels equivalent to everyone else?
I've been pleased with the NPC bard that's been tagging along with the players in the Crimson Throne campaign I've been running. I've used bards before as NPC companions for the players in 2.5/3.0/3.5 and the Pathfinder version seems more effective than those in the past, at least in a strong supporting NPC role.
CR vs. EL - This thing was always confusing to players...and occasionally flubbed me up with Monsters. This thing needed to seriously get combined into a much easier system overall...workable...but it could get mixed up at times with a bad memory...what does PF do to fix this?
Pathfinder's treatment of CR is much better than in 3.0/3/5. EL is a thing of the past now.
As I said, 3e and 3.5 were great systems. I didn't really see any reason to change...I currently play Castles and Crusades or 4e though. I did stick with the Pathfinder Adventure Paths when they were for 3e and 3.5...but when they switched to PF exclusively...I stopped buying them...as I didn't see the advantage of PF over 3e/3.5 editions. The items I listed above would be items that I had problems with in PF, or that I didn't think PF addressed.
I'm curious why you stopped following the Pathfinder adventure path after they switched to the Pathfinder Rules. Pathfinder and 3.5 are not that far apart mechanically and it is quite easy to switch things back and forth. I do it all the time with the Crimson Throne (switching 3.5 to Pathfinder on the fly). I suspect it wouldn't be all that hard to convert things the other way.
Getting back to why Pathfinder, my reasons would be :
1/ A fully supported 3.x style rule set.
2/ Better balanced classes. Revitalized for many.
3/ More reasons to stay single-classed (no dead levels)
4/ Better treatment of monster CR
5/ Options for XP advancement rates (slow/med/fast).
6/ The Combat Manoeuvrer system (CMB/CMD)
7/ Some cleaned up spells
8/ An excuse for having a break with some of the game-breaking 3.x rulebooks (e.g. Book of Exalted Deeds, etc)
9/ Sorcerer bloodlines
10/ Clerics and the Channel Energy change
11/ Hey, it's Paizo!
12/ The option to keep using your 3.x library if you wish
13/ It's all OGL! (okay, not the list of gods and Golarion stuff, but the rest of the rules are)
14/ It's the new shiny!
15/ Paizo rocks!