I really enjoyed the artwork in the Spell Compendium. That book what where I started to notice the scenes. I particularly like the assassin absorbing a dagger outside of a tavern, the cleric kneeling before a statue to pray for spells, the mass awaken scene, and the illustration for Tiny Mount. I also noticed that they're using some 'lesser iconics', such as the Wizard of Turmish, the Thayan Knight (without her tattoo), the Wu Jen, the dagger-whatevers, and a crowned lich that I didn't recognize but appears several times.
General opinions about some of WotC's artists:
Wayne Reynods: Very good action, very distinctive style. I sometimes get tired of his color choices, but overall very good.
Wayne England: Rather recognizable style. I don't mind the character portraits but I don't like the way his magic item pictures look very similar to each other. And purple. Lots of purple.
William O'Connor: I like the way he directs the action out towards the viewer. The faces on his characters are too indistinct for me.
David Martin: I LOVE some of the spell/character illustrations he did in the spell compendium. Such as this one:
http://www.wizards.com/dnd/images/spellcomp_gallery/92279.jpg One of my favorite things about his characters is that they're not wearing clothing that would require magical intervention to avoid falling off.
Crabapple McClain: Thankfully not appearing in the spell compendium. Very not my style.
I hope WotC stays with their current trend of using scenes as illustrations. I like it a lot.
-Mara