2012-03-15, 10:32 PM (ISO 8601)
Re: There's archers, and then there's THIS.
I will begin by saying that archery in D&D needs love, and I congratulate you for giving some to archery.
However, love is not the equivalent of a high-yield nuclear weapon, which is what you gave to this class at levels 10 and 15 (though not the same path, so you can't get both).
At level 10, the sniping path gets Concentration to damage. Considering how easy it is to optimize skills (see any post about Incantatrix, for example), this becomes an instant kill for anything below your CR+4 (that isn't a wizard). I would suggest adding ranks in Concentration to prevent the character from purchasing +30 to damage with minimal WBL investment.
At level 15, the archery path gets Rain of Arrows, which is the holy grail of anyone who uses attack rolls. AoE, with to-hit rolls, and can crit. I will use the example of a marrow-crushing, souldrinking weapon, used with multiple shot and rapid shooting. Assuming a haste spell or similar effect is cast beforehand (you're level 15, so this should be assumed anyway), that's 5*2*4 attacks (b/c of eagle eye)=40 attacks, all of which attack all creatures in a 3x3 block. They do get a reflex save to ignore damage, but stacking on-hit effects devastates anything in this area (seeking+bloodseeking+wraithstrike makes AC and cover and concealment irrelevant). In the above example, all creatures in a 3 square by 3 square area (9 creatures) automatically receive 38 CON damage and 38 negative levels (I'm counting 2 natural 1's here). Even if they have Evasion. Oh, and you get lots of bonus damage from Power Draw (which, because of the phrase "as power attack," lets you get bonus damage from using a 2-handed weapon, which is probably not your intent), and Deadly Skill. This is all very situational, I know, but that's an extreme example of what one can do with moderate investment and low optimization using only 3 books+core+this class.
To fix the issue with Rain of Arrows, I would suggest removing the attack roll, and have the archer make a modified check (not a skill or ability check, mind you) against the opponents AC, and the archer would receive a bonus equal to his normal attack bonus for that attack.
Also Eagle Eye lets you qualify for PrC's and feats early. You may wish to address that somehow.
I understand what you were trying to do there, but I am an optimizer at heart and wished to let you know of the issues with those 3 abilities. I believe that archers (not clerics or wizards pretending to be archers) need some love, and I support you whole-heartedly.