The Racial Variants starts with what looks like a good idea: bring back the "sub races" to D&D 4. It's a short product (12 pages). There are 6 of these subraces (here called "bloodlines"), one for each race of the PHB 1 (except for the half-elf and the human). Each bloodline has a few description paragraphs, and variant racial abilities and power.
So we have the city elf, which lives in cities as it name implies. The city elf can run on wall (which is a quite fun ability), and a power to reroll Acrobatics and Athletics checks. It seemed to me quite useless at first, but in fact, when running on the wall, you may need to make a lot of Athletics checks, so it is quite useful in the end.
Then the couatl dragonborn, which descends from couatl instead from dragons. Again a beautiful and interresting idea. The couatl dragonborn can escape grasps better (certainly because of its snake-like body), and has a new racial power.
Concerning this racial power, a lot of things to say...
a) The flavor text is "flavor text", which made me laugh. In fact, it happens with all further powers, please do something about it ;)
b) Melee bite is not defined in the SRD. Melee contact is more appropriate
c) the bonus to the attack roll should scale with the level (+4 at level 11, +6 at level 21), otherwise, the character has no chance to hit at higher level with this racial power
d) ongoing damage on a Encounter power is, I think, a bad balance idea. Encounter powers which have a (save ends) effect are pretty rare, and I think it is done for balance issues. I would remove it and change it for a minor condition
Then we have the feral eladrin, which is a more savage version of this feyish race. They fight with their bare hands and they are quite powerful at it. Concerning the War step racial power, the term "towards an ennemy" is ambiguous. Does it mean that you have to finish your move adjacent to an ennemy, or simply closer?
Then we have the sinner tiefling, which is a tiefeling that embrace its "dark side". Nothing much to say except that there are some discrepencies in how the power is written. The "Aura" range does not exists. Official racial powers are all encounter powers. The target line seems to me completly useless given the fact that the text explains the power well.
Then we have the stone-kin dwarf, which is simply the most unbalanced race I have ever seen. +3 to all defenses and resist all equal to half your level? no, please, change that. Maybe do it as a power, but not as a permanent racial ability. A racial bonus to defense should not exceed +2, and should improve only one defense. The resist all is a killer at high level.
Finally we have the timid halfling, which does not have the bravery of the other halfelings. I like the power, which is fun.
Then some talents. All make sense, but I still have a few comments and concerns
= Potent Dawn Venom = I already said that the ongoing damage was a little too much in my opinion, and increasing it by 5 just makes it blow... I would rather increase the base damage, or inflict a somewhat more advanced condition
= Surefooted = I would rather write "+2 to Athletics checks to climb". Climb is not a skill, Athletics is.
= Hellfire infreno and Blood and Fire = given the fact that the hellfire wreath is a daily power, I find that these talents make it quite broken. I would rewrite the Hellfire wreath power to make it as an encounter power, and adjust these talents accordingly.
On overall, here are my advice :
= "Flavor text" has no flavor (it is an easy star to gain)
= Not enough fluff
=_ Some powers and abilities poorly balanced