Well, at lower levels, the poor fellow is quite sad. Let's assume 3 BPs at level 1 (a +3 Con mod is reasonable). He has (given max HP) 11, worse than a fighter with a similar Con mod. He probably doesn't hit as hard as the fighter (the natural weapons are weak, and the proficiencies aren't that great), likely has worse AC, and the level 1 Beast Powers are all utility sorta things. He is a passible skill monkey, in a pinch. For at least the first few levels, the Beast Warrior is kinda behind the Fighter, Monk, Rogue, and in fact everyone else, simply because he can't deal damage.

This brings me to my second issue that I just noted: lack of damage. The Beast Warrior doesn't add anything special to damage. I mean, Psy Warriors have powers, Fighters have increased feats, Barbarians have Rage, Rogues/Scouts/Ninjas have precision damage, and even the forsaken MONK has Flurry of Blows. The Beast Warrior... can get pounce at level 4. The Barbarian can get it at level 1 and the Psy War gets it as a Power. The BW needs some damage buffs, and bad.

Finally, it NEEDS Full BAB. The Monk is not something to compare to, and the Psy War has powers, helping to negate that issue. The Beast Warrior doesn't have anything to boost that attack score.