It may look impressive (and I'm sure it is)...but wait till the carriers get it and make the usual mess of things.
Of course the "rooted" ones will be able to by-pass the usual carrier lag times.
I'll be keeping my eye on XDA Developers forum.
However new Nexus Tablet will have the pure Jelly Bean experience.
You can always buy an unlocked GSM (HSPA+) Galaxy Nexus directly from Google (just dropped price to $349) and have absolutely no bloatware and it's already getting JB today. The problem is that this means you are limited to AT&T, T-Mobile or one of the regional carriers like Cincinnati Bell.
Which leads to another point - the carriers and (I've recently learned) chip manufacturers also play a part in what phones get what OS when. Verizon is notorious for having a ridiculously tough (and costly) certification process before allowing a new device or OS onto their network.
Then you also have device manufacturers that want to put their skin on the OS and they have to do that development which takes time (and money). Which devices they decide to develop the OS for is a big factor in the whole process.
I'm currently running a leaked ICS ROM on my Bionic and it is flawless as far as I have seen in a week or so or running it. It even appears to have finally fixed the LTE/CDMA switching and data drops that have plagued this device from day one.