Having GMed/played games of all 3 (3.x, Pathfinder, Pathfinder Beta, 4e) I'd have to say that if there's things you _hate_ about 3.x, they're probably still there in Pathfinder.
Even James Jacobs said as much:
But, if you loved 3.5, chances are good you'll love PFRPG. If you hated 3.5, there's a good chance that what you hated about 3.5 will still be there in PFRPG, but maybe not.
He also noted:
That said, part of the PF RPG's goal is to remain as close as possible to the baseline of the SRD.
There seems to be an erroneous assumption going around in some circles that the PF RPG's goals are to vastly "improve" 3.5, when in fact its goals are more humble—we just want to keep in print and supported by stores the incarnation of the rules we prefer. We ARE making changes, to be sure, but those changes are mostly inspired by both our and 3.5 players' reactions not only to our public playtest, but to reactions to 3rd edition in general over the past several years.
the final PF RPG game (which is in its final few weeks of editing here at Paizo) will be closer to 3.5 than the beta was.
And that really does sum things up.
It's hard to know what to suggest, because it in part depends on what you love/hate about the system in question. For example, I know that I personally prefer 4E far more for GMing, but prefer 3.x for playing; a primary reason being that I dislike miniatures and lots of bookkeeping. 3.x has a fair amount of bookkeeping itself, but you can avoid some of it depending on the class you run and the GM does have some tricks (although not as many as a 4E one) to cut it down as well.
One of the biggest problems you're going to have is "system mastery". The move from 3.5 to Pathfinder is in my mind much like the move from 3.0 to 3.5. Putting aside any issues of whether or not it was "needed" or "improved" things, you have the fundamental issue of system mastery.
You spent however much time learning the system, getting used to spells and so forth. The change in edition suddenly throws that up in the air. Sure, lots of stuff is similar or unchanged. But you don't know _what_ changed and what stayed the same. This means that if you're the sort of person that tries to run things by the rules as much as possible, you're basically going to be second-guessing yourself and having to double-check everything. This is part of the reason that arguments that pop up about how "easy" stuff is to run (or not) in Pathfinder. Some GMs sweat the details more than others.
Can I use 3.X characters with Pathfinder with no conversion? Or tiny amount of conversion?
Sort of. Pathfinder has changed how hit dice and class (BaB) link together so you'll want to double-check that, check the skills due to changes in the skill points and what skills are what, and double-check the feats to make sure they're actually doing what you think they are. Class abilities have changed as well (casters especially get some more stuff), so if you bring a pre-existing character over you're going to need to add stuff to it in addition to the skill and possibly HD/BaB changes.
Can I use 3.X crunch materials (prestige classes especially) with Pathfinder with little conversion?
About like converting over a regular character. In this particular case though, you're going to have to watch out for the prerequisites and decide how you want to handle them; there's a strong chance you're going to need to figure out how you want to shift the Hit Die/BaB since they're likely to not be aligned the way Pathfinder does them.
Does Pathfinder keep skill points allocated level by level and some synergy bonuses?
As I recall (I haven't played/run Pathfinder/D&D for a while) You no longer gain four times the normal skill points at first level. Instead, every skill that is a class skill and has at least one point in it gets a +3 bonus to it. There is no penalty for cross class skills anymore, just the benefit that is gained by putting one rank into a class skill. No synergy.
I also seem to recall that anyone can track, find a mechanical trap, and disable devices with the skill, only rogues can do magical traps. The fellow that usually plays rogues squawked when this popped up.
Does Pathfinder have any way to make a druid that cast spells a little bit, Turns into goonish forms for battle and gains skill bonuses in certain forms for scouting and sneaking? Are wildshape forms just as complicated, involving math of multiple spread sheets to compute?
I can't speak to this at all, since I've flat out just not had Druids in my games. I personally hate it when someone starts pulling in non-core (as in not the main rulebook but a supplement) books, but there's some sort of Summoner class that's been done; it comes with some funky critter, the Eidolon. You might be able to get _that_ combo to do what you're talking about with the Druid. These days I refuse to buy splats without a genuinely compelling reason, so I've no clue if any of the Pathfinder splat books are any good or not.
Again, whether or not to make the switch really depends on what you're looking for.
Pathfinder: Ignoring any subjective opinions about Pathfinder being "better", it's currently being published and has new stuff being put out for it. If you're willing to do some work, you can use 3.x materials in the Pathfinder system. The amount of work required is going to depend partially on your own tendencies to be exact, as well as the nature of the material you want to convert.
3.x: You've presumeably already got system mastery of this. You'll have a minimum amount of effort to get back in the saddle and a few more years have gone by, so there may be better solutions to some of the problems. You can bring Pathfinder stuff over to 3.x in bits and pieces if you want; even Pathfinder monsters to 3.x shouldn't be too much of an issue although there are differences.
4E: It's also currently getting material published for it. The overall design is much more coherent than most of the 3.x systems, including Pathfinder.
As a good DM should.
