Ok guys I saw that some of you don't like the half elf so much just because he doesn't take anything to the next level, But I like him just because of that, he is a pure character to pick by style of playing, not for any special other reason... Here - I'll write some classes with half elfs VS same classes with the most obvious race to choose and tell why it's possible to pick half elf anyway.
Half elf assassin rogue VS Halfling assassin - For some reason no one considers that, so here are my thoughts -
Differences - Halfling gets the guile and the AC and attack chance bonus - While the half elf gets the extra bluff.
So obviously in math halfling takes it, more damage on sneak and even more bluff skill thx to guile so in most cases people will take the halfling - BUT there are some and some ways to play an assassin, I know people who just hates the aggro, HATES IT - and every time a monster comes out of the line and aggros them they must run circles or try to kill it slowly.
So if ur that kind of player, the one who hates when he have to handle 1vs1 monsters - with halfling ull get the little more bluff skill and even alittle more melee power - while with half elf ull get only another bluff button with slow cooldown.
So lets imagine it now - ur in the middle of a rough fight with aparty that barely handles, and a foe (lets say human) is running at u - as an halfling ull use bluff, give him a hit and start fight with aggro against him till the cooldown will be over.
As an half elf asme thing happens, but u can use the bluff after bluff right away, means ull gain 50% more sneak attacks while fighting aggro with a monster (more like 45% more cus of the less bluff skill overall) - total meaning ull make much more damage in a combat going out of the line.
I know I know, not alot of people would see it as something good or even a bit - specially not the pro's, but im sure we all can imagine someone who wants to open a rogue but he dont wanna be too careful in fights - means he'll get more 1vs1 aggro than other rogues - means half elf assassin might be right for him.
Edit: Also extra diplomacy use, which will really help their style of playing this character - as a rush rogue you might get much more aggro than you can handle - Extra diplomacy will help you dropping it easy.
Ill stop digging a little with my thoughts now and explain more general.
Battleclerics could be half elfs - thanks to the fact they have the fighter feat which will give them the possibility to remain cleric and gain all the cleric stuff to lvl 20 + get the weapon they always wanted for fighting foes. So yes - some will say "I wanna go fighter all the way to kensai and rest cleric" But still - battlecleric half elf is a decent way of playing, its alittle less tough but much more cleric - which will fit the style of some and some players.
Same thing about battleWizards, rare as they are (and tho i dont like them). And same thing about the battleBards, they now can remain theyre class and get all the benefits they want till lvl 20 from it, but still remain fighting melee.
I could think of a few more examples to give - but here is my point - Half elfs doesn't take anything or any class up to the top(except the tank half elf - they should take the tank into a higher top probably), its a race for fitting to some game styles, it's a race to make to gameplay more wide and interesting and i have no complains, I like it.
Edit: something I don't like about them: their look, human body and crappy gentle anime face... just... fix it...
Oh btw, even tho what i said - I do think they don't have good enough enhancements (More like... uncompleted), so here is an enhancement i thought of, hope devs will take interest.
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Enhancement: Giant confidence
* You're confidence shine above you as a massive aura, giving you size bonus to half elven intimidate, means you will not suffer any penalty when intimidating bigger creatures than you up to the size of giants, Also you will get a bonus intimidating creatures below the size of giants.