Dawkins can easily be accused of using these very weapons in The God Delusion and that is why it was so vociferously attacked.
Yes, Dawkins is an expert biologist. I enjoyed reading his books on biology.
Creationists criticized Dawkins for his arguments on biology. However, the criticisms that I see now, criticisms coming from philosophers and theologians have to do with Dawkins' attempt to argue philosophy and/or theology. He speaks with contempt about theology and then tries to refute certain of its claims.
For instance, my copy of The God Delusion is Houghton Mifflin 2006. On page 77, he tries to refute Aquinas' unmoved mover argument (The ellipsis in the quote just covers Dawkins' presentation of: The Uncaused Cause argument and The Cosmological argument):
All three of these arguments rely upon the idea of a regress and invoke God to terminate it. They make the entirely unwarrented assumption that God himself is immune to the regress. Even if we allow the dubious luxury of arbitrarily conjuring up a terminator to an infinite regress and giving it a name, simply because we need one, there is absolutely no reason to endow that terminator with any of the properties normally ascribed to God: omnipotence, omniscience, goodness, creativity of design, to say nothing of such human attributes as listening to prayers, forgiving sins and reading innermost thoughts. ...
Aquinas in Summa Theologica on Question 2 Article 3 (his unmoved mover argument):
The first and more manifest way is the argument from motion. It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another, for nothing can be in motion except it is in potentiality to that towards which it is in motion; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must needs be put in motion by another, and that by another again. But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.
They make the entirely unwarrented assumption that God himself is immune to the regress? The whole argument leads to the conclusion that there is a need for an unmoved mover. You can call the argument invalid; but you can't claim the claim that the conclusion is an entirely unwarrented assumption.
As to his claim about the lack of argument for the attributes of God, here is an excerpt from the Table of Contents. The attributes are derived based on the arguments given with respect to the existence of God (i.e. the one's Dawkins is referencing):
4. The Perfection of God
5. Of Goodness in General
6. The Goodness of God
7. The Infinity of God
8. The Existence of God in Things
9. The Immutability of God
10. The Eternity of God
11. The Unity of God
12. How God Is Known by Us
Dawkins' claims here (and elsewhere) are just wrong; and 5 minutes of research would tell him that. This is not to claim that Aquinas' arguments are right. They have been rather famously refuted - for instance, by Kant. Dawkins could have just cited Kant. Instead he tries to refute the argument himself and fails even to state it correctly.
So, yes, The God Delusion was attacked for the sloppiness of its arguments.