Alright, two days after I've read the rules and I've calmed down completely now

Took a lot of time to rethink the system, and here are my thoughts:
The Initiate Feat
Thinking about it more, I'm okay with this feat. There are some advantages to it. For one, you can multiclass at 1st level, something you couldn't do in 4e. That's a plus. Second, the potential for balance is much higher than before. Now, whenever we get new classes, we should expect a multiclass feat to go with it. Using that, everyone class should be a balanced option compared to each other. Definitely a plus.
Frankly, the feat couldn't be any stronger, or it would be a must have.
I still believe that the biggest problem with the feat is twofold.
1) That the initiate feats are not balanced with each other. But I'm a man a of science, and I recognize that seeing a few words on a page, when we may not even have the full text of the feats, is a poor judge of balance. I'm big enough to admit a wait and see approach is a better judge.
2) That the multiclass feats don't allow enough mixing of the classes. I'm of the opinion that multiclassing is a patch for the class system. The class system provides a lot of benefits, but its biggest drawback is each class provides a limited archetype. In order for players to play the character they want, you need to blend those archeytpes a bit.
I get that one feat is not enough to do a full mix of two classes, nor probably should it for balance reasons. But I think we can do a bit better than what we have here. For example, allow a second initiate feat to pick up another class ability (again strict control on which one).
Or force the person to give up something from their original class to gain a bit more in the multiclass. For example, let's say that every class has an * next to one of their class abilities. The fighter's +1 to attack for example. Then the multiclass feat would allow you more strength in your multiclass, but at the cost of some of your original ability.
For example, change the Ranger feat to the following:
Ranger initiate feat (forgot the name)
Prereq: Str 13 or Dex 13
Benefit: You gain skill training in one ranger class skill you currently don't have training in. Once per encounter you can use the hunter's quarry ability.
Special: If you give up your * class ability, you can now gain the ranger's tactic ability (TWF or archery).
Multiclass Powers
My opinion is still that 3 feats to gain 3 powers seems weak. However, once again until I see the full feat system and what kind of awesome wizard powers I can get for the fighter it would be ignorant of me to create strong judgements.
One thing I would like to see is a "practiced spellcaster" type feat that would allow multiclasser some help getting their new powers up to speed. For example, a fighter with an 18 strength and 13 int may love his new wizard power, but its going to be extremely weak comparatively (both in damage and in attack roll). Perhaps a feat to bump that power as high as your primary stat or something of the note.
If a person is willing to spend all of those feats to get a power, then he should be entitled to be good at it.