I will admit that I don't know how playtesting/development stages work. The only actual playtest I've ever witnessed is the one for the Dresden Files, where they took the alpha rules, handed them to playtesters, said "Use these rules, break them and show us their flaws," then revised, released a second round, gave the new rules to new playtesters, said "Break them, show us the new flaws," and plan on doing it a third time.
So all this talk of "The Beta is the first time it's going to get played!" is odd.
But I must say I'm getting a kick out of the responses of "Don't criticize paizo/the rules". Apparently criticizing playtest rules is bad. Especially from a concise, fair, and reasonably said OP. As the PFRPG comes out, I'm certain more discussions like this are going to come, and it's going to be tedious to see fair criticism get beaten up.
Well, Paizo isn't telling you to quite criticizing. Besides, I saw the responses you seem to be talking about aimed at people who just pop into the thread and say, "I hate the changes! Pathfinder sucks!".
Plus I thin it would help if people really remember what Pathfinder is for. A rule book to help keep the 3E community alive.
If you love 3E the way it is, or have moved on to 4E, or some other system, Pathfinder is not being written for you. Its being written for people looking for changes, or looking for a 3E compatible book with which to use 3E books.
If you go to the end of the Beta PDF and read how Paizo says to use PF with 3E its really not hard. Just add 1 HP per level to classes, add a couple of feats/skills as levels go up, etc...
Nothing that I see actually increasing the difficulty. Plus I think Paizo has done a MUCH better job of explaining skills, feats, and combat actions.
So I think the final Pathfinder will be a rule book that is written much more clearly, containing new rules, better written skills, feats, combat actions, etc... then the 3E PH and DMG, so will be, over all, a superior rule book for a 3E game.
Even if I was still a 3E die hard (I died in early 2005) I would want Pathfinder simply because Paizo is doing a superior job in the presentation, let alone a bunch of cool "alternative" rules and class versions.
I'm not a 3E die hard, and I still intend on buying the final book. Simply because I think even what is kept the same will be written in a superior fashion.