New Skins in the Store

Royal Guard Fiora
Nightraven Fiora
Bladecraft Orianna

Yay, finally a new Ori skin!

PVP.net v1.55

Ranked Teams
Fixed a bug with the background on the Team Invite popup
Fixed a bug where Team status would be missing on the Team Profile
Fixed a bug where Ranked Team specific notifications would not send properly
Fixed several bugs with client side stat calculation and display

So when is riot going to make a client that actually works?

League of Legends v1.0.0.135

Fiora, The Grand Duelist

Duelist (passive) - Fiora regenerates health over 6 seconds each time she deals damage. Striking champions will cause this effect to stack up to 4 times.
Lunge - Fiora dashes forward to strike her target, dealing physical damage. Fiora can perform the dash a second time within a couple seconds at no mana cost.
Riposte - Fiora's Attack Damage is increased. When activated, Fiora parries the next basic attack and reflects magic damage back to the attacker. Works against champions, monsters, and large minions.
Burst of Speed - Fiora temporarily gains additional Attack Speed. Each basic attack or Lunge she lands during this time increases her Movement Speed. Killing a champion refreshes the cooldown on Burst of Speed.
Blade Waltz (ultimate) - Fiora dashes around the battlefield to deal physical damage to enemy champions. Successive strikes against the same target deal less damage.

Alistar

Triumphant Roar mana cost increased to 28/41/54/67/80 from 20/35/50/65/80
Unbreakable Will mana cost reduced to 100 from 150
Trample damage increased to 10-27 per second from 10-23

Riot really doesn't like passive lanes, do they -- slightly rewards agressive play as Alistar, over passive play. Doesn't actually change his function much. Overall, probably a small nerf.

Fizz

Base damage increased to 56 from 54
Armor per level increased to 3.4 from 3.1
Churn the Waters mana cost reduced to 100 from 150

Massive early game buff to Fizz. In my opinion, he didn't need it, but I don't think it quite overpowers him either.

Galio

Idol of Durand damage range increased to 600 from 575

Minor buff, probably as compensation for the visual appearing to be around 600 range.

Irelia

Fixed a particle issue with Transcendent Blades (Hotfixed 2/21)

Bug fixes are good.

Jax

Fixed a bug where Grandmaster's Might passive attack canceled if the buff ran out during the attack animation

See previous statement.

Lee Sin

Sonic Wave base damage increased to 50/80/110/140/170 from 45/75/105/135/165 (Hotfixed 2/21 due to an unintended nerf in the Nautilus patch)

As are human error fixes.

Lux

Lucent Singularity
Now additionally grants vision while in flight to its destination
Now starts its cooldown when cast rather than when detonated
Cooldown increased to 10 seconds from 9
Now displays a buff showing how long Lucent Singularity will last until it automatically detonates
Finales Funkeln
Now grants vision of the affected area during the spell and vision of enemy champions hit for a short duration afterwards
Lux can no longer use Flash while casting Finales Funkeln

Slight buffs to the utility of Lux, while very slightly nerfing her nuking capabilities. Overall, probably a slight buff.

Malphite

Granite Shield now shows a cooldown timer
Unstoppable Force
Area of effect radius on impact increased to 325 from 300
Malphite can no longer flash while using Unstoppable Force
Fixed a bug where Malphite would seem to hit the target but would not cause the effect

Slight nerf to Malphite. Not a make-or-break change. The Granite Shield timer is quite a nice addition.

Miss Fortune

Strut now shows a cooldown timer

Yay, usability buffs.

Nocturne

Umbra Blades now has a passive cooldown timer like Ziggs and Shen

More usability buffs!

Olaf

Axe Throw
Damage increased to 80-260 from 50-210
Scaling changed to +1.0 bonus AD from +0.5 total AD
Base cooldown reduced to 8 seconds from 10
Cooldown reduction for picking up the axe reduced to 4.5 seconds from 6
Ragnarok now provides 30/45/60 Armor and Magic Resist instead of 20/30/40 flat damage reduction
Movement Speed increased to 325 from 320

Pretty large buff to Olaf, encouraging building a bit more AD on him than before, as well as encouraging building health over resistances a bit more. (flat damage reduction scales better off resistances, whereas armor and magic resist scales better with health).

Poppy

Paragon of Demacia now shows you over its icon how many stacks you have

Usability buffs!

Shen

Fixed a few bugs with ability sounds
The following changes were hotfixed out on 2/21:
Base armor reduced to 19 from 23
Vorpal Blade health scaling lowered to 1.5% from 2%
Feint Energy cost increased to 50 from 40 at all levels
Base shield value reduced to 70/115/160/205/250 from 70/120/170/220/270

He's still really stupid strong, if you don't build like a dweeb.

Teemo

Health per level increased to 82 from 77
Move Quick's passive component now shows a cooldown timer
Noxious Trap arm time reduced to 1 seconds from 2

Fairly large agressive teemo buffs, especially the Noxious Trap arm time reduction. He's now even more obnoxious!

Tristana

Explosive Shot cast range increased to 625 from 600

A good usability buff. Explosive Shot was always hard to land at higher levels, due to its low(er) range.

Ziggs

Hexplosive Mines
Mana cost reduced to 70/80/90/100/110 from 80/90/100/110/120
Slow duration reduced to 1.5 seconds from 2
Damage from 2nd and subsequent mines reduced to 40% from 50%
Fixed a bug where Ziggs' Mad Scientist skin was leaving particles on the map (Hotfixed 2/21)

A slight nerf to Ziggs. Champions can now escape his mines more easily, though he can spam them a slight bit more.

Items

Madred's Bloodrazor attack damage increased to 40 from 30

It's still far from cost effective. -- Still never rushing one.

General

Improved minimap visibility of turrets in Colorblind Mode
Colorblind announcement colors now reference blue (friendly) and purple (enemy) teams
Important items purchased by your team will now be called out in chat (Aura items, Sight and Vision Wards, top tier items, etc)
Champion Kill messages are now more specific
You can now activate a timestamp for game chat in the options menu
When colorblind mode is activated, movement cursor is included with new color scheme (was not before)
Announcer callouts no longer reference blue team/purple team, and instead should reference friendly/enemy team (ie. A friendly inhibitor is respawning soon/the enemy inhibitor has respawned)
Champions will now attempt to run home immediately when disconnecting, rather than attempting to Recall
Small monster camp sigils now restore up to 30 Mana in addition to Health
Small Golem camp
Movement Speed increased to 300 from 180
Medium Golem base damage increased to 59 from 54
Fixed a bug where whisper messages were the wrong color

Yay, usability buffs! Notably, the chat call-outs. These will help the less coordinated teams keep up a bit :P. Jungle buffs for mana junglers! Definitely a good buff in my opinion, as it enables a few more junglers to sustainably jungle (and to share their blue). Small Golems will also be much harder to take now. I like this change, as blue side bot lane always had an advantage coming into lane, as they could opt to take their own double golems and be half a level up initially. Now, it's a bit trickier.

Co-Op Versus AI

Added Blitzcrank bot to the roster of bots in Co-Op versus AI.
Improved bots' ability to last hit and reduced how much they push their lanes.
Reduced the amount of gold given to bots on Summoner's Rift Intermediate.
Added the ability for bots to call for help from nearby bots.
Improved the precision of skill shots and ground targeted AoE abilities.
Minor bug fixes with Leona, Lux, and Shyvana bots.

Yay, AI updates.

Art

Fixed animation bugs on the following skins:
Toy Soldier Gangplank
Jade Dragon Wukong
Superb Villain Veigar
Headhunter Master Yi

And finally, Yay, bug fixes!