There are a lot of options, which is good and necessary for a game like 4E, but it depends on the class you're playing.
Load up the Character Builder and stat up a fighter, first level is fine, and then stat up a paladin. What do you notice? Two of my three 4E characters are divine (cleric and paladin) and the lack of interesting choices for them compared to my fighter is painfully obvious. It's laughable that if you build a human divine character that third at-will you get to choose is all but useless as you're unlikely to have the attributes to make it a viable option compared to your "prime" at-wills.
WotC need to formulate a better way of releasing class options. Additional power source books will be needed to support the introduction of new power sources and new classes added to existing power sources in future Player's Handbooks.
Looking at the 2009 schedule it seems they're trying to release a power source supplement every three months. If they can maintain that schedule then by the time Player's Handbook 3 is released we'll be looking at fifteen months between power source specific supplements for each source, assuming they stagger them. Each new power source would add three months to that.
I think they should consider structuring the power source supplements similar to Player's Handbooks and have three sources per supplement.