At first blush, this is my take as well:
Several Democrats, including Reid, have already come out praising Miers, which ultimately will only fuel the right-wing meltdown on the decision.
I reserve the right to change my mind, but Miers' biggest sin, at this early juncture, is her allegiance to Bush. That her appointment is an act of cronyism is without a doubt, but if that's the price of admission to another Souter or moderate justice, I'm willing to pay it.
More immediately, this is the sort of pick that can have real-world repercussions in 2006, with a demoralized Republican Right refusing to do the heavy lifting needed to stem big losses. That Bush went this route rather than throwing his base the red meat they craved is nothing less than a sign of weakness. For whatever reason, Rove and Co. decided they weren't in position to wage a filibuster fight with Democrats on a Supreme Court justice and instead sold out their base.
We'll have several months to pick through Miers' record, as well as highlight her role in any number of Bush scandals (like Georgia10 notes).
But my early sense is that this is already a victory -- both politically and judicially -- for Democrats. In fact, it should be great fun watching conservatives go after Bush. He may actually break that 39-40 floor in the polls, given he's just pissed off the very people who have propped up his failed presideny.