Although the 30-40 bracket is much like the 20-30 bracket, at least you start to get some interesting new abilities like Ravage, Pounce, Feral Regen, Ferocious Bite, Track Humanoids, Dire Bear form, and Innervate. Instead of finishing mobs with Rip you're probably more apt to finish them with Ferocious Bite. And you're probably more apt to open up with Pounce (ignore Ravage all together) instead of Claw and take less damage over all during any particular fight. Especially as Pounce is particularly useful in PVP.
The class still suffers from a lack of cat form AOE and it shows in dungeon runs. No one is running around at level 35 or 40 watching damage meters, but if you do you can see those classes with good AOE capabilities far out and head of the single target classes -- Cat Druids being just one of them. Boss fights are a different story however. By this point Shred is a staple ability, but the directional limitation is as much of a problem today as it ever was. Particular on movement fights, or where you have a lot of spell effects going off that might obscure the boss if there is just a small amount of movement. Blizzard has said before that the analog for Shred was Back Stab, but no Rogue at this level is running around Back Stabbing and once a Dagger Rogue gets Mutilate they'll never use Back Stab again. Whereas Cat Druids have to use Shred. I see that Blizzard is planning on making Mangle more able to replace Shred so I'll take that to mean they have no intention of removing the direction requirement any time soon. Too bad as strict directional attacks like Shred have high down sides.
The addition of Feral Regen is very nice, and you'll come to appreciate it as most healers on low level dungeon runs are healers in name only and prone to mana issues. On those fights where you end up as an OT or THE tank, Feral Regen comes in quite handy. Being able to pop a health potion in form now is gravy on top of that.
And the best thing about hitting level 40..... dual spec!