here are some of my observations with my 900BT...
A. My iPod, 30gig video classic 5th gen, works about 50% of the time on boot up. This might be due to the fact that I leave it connected in the glove box all the time, and its cold outside right now, sometimes below freezing, which might have something to do with it. We'll see if that changes in the summer. I'm gonna take my iPod to the apple store to see if it needs a firmware upgrade.
B. Bluetooth, I have a Palm Treo 700wx with the new version of mobile windows, sometimes it connects, sometimes it doesn't. I try to get it to manually connect from the head unit and from the phone, but it is stubborn, then occasionally it just recognizes the phone on its own while driving down the highway. When it is connected, the sound is flawless on both ends.
C. My contacts only show the last name, first name, multiple times for each number. I read that others can see whether its home, cell, office. I havent figured out why they can see this and I dont, can only assume that this is a phone specific problem. Or maybe my icons are too large, if there is an icon shrinker function or a way to show the names in a list, please let me know.
D. Clock is way to small, but i read that there is a hack to make this bigger, but I'm not much on messing with the thing cause I dont know what i'm doing. So I'll wait for the next firmware update and hope that its fixed.
E. Boot up time is palatable, see no major issues with a little wait. Since I didnt have the first version and moved right into a unit with the 2.0 installed when I bought it, I dont have anything to compare to.
F. The voice of Samantha is down right irritating and too computerized, to the point where I would rather leave it on Jason.
G. Dialing in the volume of the voice navigation takes some playing with, it should just be based on the speed of the vehicle instead of setting low and high limits. I'm still working on this one as I don't use the navi all that often cause I go to the same places over and over again.
H. In 3D mode the triangle icon for the car is WAY to big.
I. 3D mode is the only mode that the directional car icon points in the direction you are visually looking, they should make this for the 2D mode as well. My hand held unit does it, all you do is tap the compass icon on my handheld and it switches between true north and visual direction.
J. The EQ is too difficult to get where I want it, you should be able to independantly move each bar as opposed to having several of them move simultaneously, and for goodness sake, its a touch screen, i should be able to slide the bars up and down using the screen as opposed to pressing the selector buttons on the touch screen that move several at once, and not necisarily where I want them.
K. Presets should be listed on the main audio screen where the picture resides of the channel your listening to, thre is blank space there, they should use it, I shouldn't have to navigate to the preset screen, or press a button that says P so I can scroll throught tme till I find the one I want.
L. the mode button for XM works great, I added several of my favorite songs and they always pop up regardless of what channel the're on.
M. the ting sound that goes on everytime I use my steering wheel controls to raise or lower the volume, I haven't figured out to get this to go away yet.
N. the volume control knob is too shallow for my sausage fingers, too hard to grip and turn, thats why I use the steering wheel volume control
O. the light scheem, there should be more lights, its a waist to have a cool light set up if its only going to be in the upper left corner, they should put a couple more lights around the head unit just for show.
P. Voice recognition for the phone doesnt really work unless I say dial #######. Saying the name is useless, doesn't matter what name I say. But then again, I typically call the same people over and over again, so its not that big a deal. But it would be nice to say Call Jackies Cell, and actually have it work. My onstar system works flawlessly for this, don't know why this unit wouldnt.
I think that about sums it up for now, if I come accross any others I'll be sure to post back. And if i find that my iPod firmware update solves the boot up issue, I will post back as well. All should keep in mind that in no way do any of my observations detract from my like of this unit, I truly like it, and I would still buy it again knowing these issues hindsight. These are just things that I noticed that Pioneer might want to pay a little more attention too in the future. And if anyone knows how to correct any of these items in a simple way, please let me know, you can either PM me or point me to a post that is relative to my unit, the 900BT.
Thanks,
Be kind to your fellow posters, this is suppose to be an informative forum, thrashing each other doesn't help anyone, and it certainly doesnt solve anything. 
Don