Well for starters the cataclysm changes that were revealed in a blue post not too long ago came as a bit of a let down to me. I think a lot of it is that they just aren't telling us everything yet and in those hairy details are where my concerns lie.
First off, one thing that bothers me currently about a lot of stats is there isn't a good way for your average player to figure out how much of a certain stat they need without going to a third party source. It is fairly easy to discern which stats we want, like agility is really nice for feral druids, but when it comes to things like expertise and hit there comes a point where intuition has diminishing returns.
The mouse overs do a good job of explaining what the stat does and hitting more and getting dodged or parried less sounds wonderful, but shouldn't there be some indication that your chance of missing or of being dodged or parried is reaching zero? It is a good thing there are people that have nothing better to do that play dress up and whack things for hours to find out something blizzard already knows. Doesn't sound much fun to me, but then again I'm not much of a theorycrafter. Metagaming kills immersion and all that jazz.
The main problem with showing some concrete percentages is that those values are a moving target depending on what you are hitting. But it just so happens that Blizzard made monster avoidance based entirely off of level, targets of lower level are easier to hit and targets of higher level are harder to hit. So unless some oddball creature out there breaks with tradition displaying meaningful data to players is sort of trivial.
Show the lowest chance to miss, be dodged or be parried along with the level that percentage is based on. This way you know that anything of a lower level you are guaranteed to hit, not be dodged or not be parried and anything with a higher level would have a larger chance. It's not really important to know an exact number for every level so long as there is enough information there to know if you've hit a cap or not and about where you are. Along with that % in the tool tip keep the arbitrary stat values more or less (more on that next) as they are convenient for quick comparisons with known values once those known values are derived.
This type of information would be especially handy on the fly while leveling where there isn't a whole lot of information available since all the thoerycrafting is done at max level. Sure there are a few formulas derived that can be applied to lower levels, but who is going to do that?
The second issue I have with the current system of stats aside from all the values given being completely arbitrary is that there is not one, but sometimes two and often three arbitrary values for the same thing. Hit rating, melee hit and spell hit for example. If you count arbitrary percentages that is four arbitrary values.
I can accept that casters require more hit rating even though I am not sure why that needs to be the case, but what I don't understand is why there needs to be a second value to represent hit rating in another form. What this leads to is one stat on my gear which I have to convert to figure out what the end result will be on the final stat. This is easy enough with gear when you just try it on, but when you are trying to figure out which gems or enchants to place on your gear it quickly becomes overly tedious. In addition to a simple addition/subtraction there is an extra multiplication/division by some arbitrary conversion factor which once again must be derived or obtained by a third party.
With any luck Blizzard thought of all that and just didn't tell us, but I doubt it. Lets get back to what they did think of though.
I like the removal of armor penetration, attack power and spell power. Trying to remember for each class which stats had a 1 or a two conversion factor from base stats was never easy, especially when it changed. It is also nice to compare apples to apples rather than weigh the pros and cons of two stats that basically do the same thing in a different way. Those changes are really nice. Spirit and MP5 fall into the same category. Now if only hit rating, melee hit and spell hit all became simply hit.
Removing defense was nice for bears, but I'm not sure it really mattered for anyone else. Bears lost defense because they were tired of making defense leather for one half of a talent tree of one class. I'm surprise they haven't found a way for holy paladins to heal with strength and regen with stamina. Anyway, as a result of not needing defense there is a lot of gear with defense on it like necks and rings that we bears would rather see with straight up dodge. So if all the defense on ring and necks or at least on more items is turned into dodge, bears win! If they convert it into a mix of dodge, parry and block then it is a wash. I would imagine a lot more bear friendly gear comes out of this change though.
The other main part of the changes was there is a whole lot less choice as to what gear people should be wearing and with that lessened choice there is a lot less work for Blizzard to do in coming up with loot. My guess is that nothing much will come of that besides less gear to chose from considering the emphasis that has been placed recently on how many different pieces of gear were created. I am hoping though that that effort usually required to appease a few specific classes/specs will be put toward making more interesting procs and effects for everyone. I've seen a few blue posts promoting weapon and trinket procs as something they enjoy playing with, maybe procs on armor could be next, who knows.
It could just be that the reduced workload on gear will be redirected towards other things like the world being blown apart. The world only blows up once though so those content patches have the opportunity to have some really neat stuff.