Not me. Plant creatures aren't subject to critical hits, mind-affecting spells, or death from massive damage.
Unless it's been changed for 3.5 - when you change shape, you do not change type. Which means you don't get that type's immunities. I personally think that you -should- change type (Uh.. Bill? I just crit on this ooze.. something's not right here.) - but that's a different discussion.
Hell, a clever 3.5 druid can cast the new call lightning, wild shape into a shambling mound, and zap himself with electricity to heal during combat. Some juicy possibilities there.
Not if Wildshape doesn't grant EX abilities - Electricity Immunity and the con-boost it gives Mounds is extraordinary.
Plus, dire animals are generally cooler than normal ones, and I for one can't wait to wild shape into a dire lion at 8th level. A freaking dire lion! Rawr! And imagine this: 3.5 druid is a dire bear - he improved grabs opponent, pins him.
An Ex ability, so he doesn't get it.
Shapeshifts into a dire constrictor with no need for a Concentration check. Squeezes the Charmin' until its eyes pop out.
and likewise, Constrict is Ex also - so he doesn't get that either.
If you get no Ex abilities, then a druid gets no rake, no pounce, no scent, no improved grab, no trample, no blindsight, no sprint, no ink cloud, no jet, no constrict, no poison, no attach, no trip, no swallow whole.
Frankly, they should put a tag [Natural] onto abilities so you know which ones you get when you Polymorph, Shapeshift, Alternate Form, or Wildshape into that creature. Dog: Scent [Ex, Natural].