Sadly, however, these six classes are not the ones I would have chosen, and although I think some of their ideas were good ones, they highlight to me much of my dissatisfaction.
Most of the D&D (and therefore Pathfinder) basic core classes use some kind of magic. In fact, of the eleven core classes, only four of them do not have a spellcasting progression of some kind, and of those four, one of them (the monk) still has a buttload of supernatural abilities anyway. For low magic options (or just for people who don't want to mess with spellcasting in their character), then, that only leaves a bare three classes: the barbarian, the fighter, and the rogue. It's no wonder, then, that I'm a big fan of using some alternate classes. The Scout, the spell-less rangers and paladins, the Swashbuckler, various ninja or assassin alternate classes, non-supernatural alt.monks; these are all some of my favorite alternate classes to integrate into my games.
It's perhaps not too surprising, then, although disappointing, that the alternate Pathfinder classes are also almost exclusively magic-using classes, and the only one that isn't, really, is one that's not really up my alley at all either. The six classes are the Alchemist, the Cavalier, the Inquisitor, the Oracle, the Summoner and the Witch. The Alchemist technically isn't a spellcaster (although his impact in game is very similar to a spellcaster) and the Cavalier is obviously the same concept (if not exactly the same execution) as the 3.5 PHB2 Knight. The Oracle is a more shamanistic like divine spellcaster, the Witch is an arcane caster that borrows heavily from fairy tales (I actually quite like the Witch as a spellcaster, to be honest with you) and the Inquisitor is kinda like a darker, grimmer version of the paladin, except with slightly lesser combat stats and slightly better spellcasting stats.
The summoner is also (obviously) a spellcaster, but surprisingly, he gives up some spellcasting ability to be able to bond with a strange extraterrestrial entity called his eidolon, which can take many forms and fight (or whatever) in his behalf.
The mechanics for all of them seem solid enough, but conceptually, I was just disappointed in what they decided to follow. The Pathfinder setting mentioned psionics (briefly) yet we still have no Paizo psionics. These classes continue to ramp up the presence and ubiquity of magic (sadly... at least to my sensibilities), and we are still lacking some really basic core archetypes (I think a good swashbuckler is a more core archetype than many of the ones we do have, and it always disappoints me to see it neglected.)
Of the new classes (again, Beta 2 version, not final) the summoner, the alchemist and the witch are the ones that interest me the most, because they seem like stronger concepts that have some more notable differences to what's already in the game, and are strongly rooted in folklore and fantasy fiction.
The image, by the way, is one of Wayne Reynolds for the new core classes, the Oracle. Although its the only one to be released digitally so far (on the Paizo blog), we've seen pencil sketches of all of them, and there are new, small, images of all six in color in the backs of the latest Paizo books.