I got it and had nearly a week now to test it.
I have to fully agree with what has already been said about the M3000:
Excellent sound and amazing noise cancellation!
I tried it in a work cantina where with any other headset you can hardly hear my voice through the background noise. You can still hear some louder noise with the M3500, but as soon as I start talking the background noise completely fades out (according to my wife), and the voice comes through perfectly clear.
So if you are looking for good sound, this has got to be the one, and for me it's 10 out of 10 for sound.
Goodies:
It comes with a regular charger AND a car charger, and also with a belt clip which I find very useful.
There's a few minor things and one major negative one.
The big one:
Comfort.
It comes with two hard plastic earshaped loops, two sizes, both with a rubberized area on top. A small loop hooks up to the earpiece, and this pushes the earpiece nice and close to the earcanal.
Unfortunately even the large size is just a bit too small for my ear.
Also, the little ring that holds the headset is positioned just a bit too close to the outer ring, so I am having a hard time getting the piece exactly into my ear canal. After a while I have to change positions. Definitely not good for keeping on the whole day, at least for my ear.
I will try to find a place that can custom-make plastic parts, and I'll ask them to make the same loop but with the inner ring further apart - that should make it a perfect fit.
Smaller ones:
It seems to me that the little speaker is always on and receiving very quiet radio waves of some sort. If I sit close to my laptop, the sound (while not using the phone) becomes just a bit louder. It's still very quiet, but I have very good ears. It's a tiny buzz, nothing I would return the headset over, and I only notice when it's really quiet around me.
Battery life is pretty short. I had it run out on my recently on a day when I maybe used to for 2 hours spread throughout the day.
Good news is that it comes with a car charger.
Not sure if this is my Blackberry or the headset, but once I disabled the connection to save battery on the headset and put it into my belt case. Half an hour later the phone rang and I picked it up and couldn't hear anything, later realizing that my headset must have connected again. I know I disconnected it before...
Summary:
Best sound I could imagine.
Not so good comfort - I'll try to find ways to deal with this because the sound is worth it in my opinion.
Comes with car charger and belt case.
I bought mine on
www.thenerds.net, partially because of their return policy.
BTW: If anyone knows a place that can customize plastic pieces, please send me a PM