The Echo smartpen is the latest in Livescribe's range of smartpens and carries with it a few improvements over the Pulse
(the "old" smartpen). The improvements are:
1) A flat area on the bottom of the pen to prevent it from rolling over.
I have used the Pulse for over a year and while its functionality is great, I often had to place the pen in its carrying case when I wanted to put it down during lectures to prevent it from rolling off the desk. This used to create a scratching sound on my audio which while not detracting from the recording, would be highly annoying when re-listening to sessions. No such problem with the Echo. You can put it down and even if it does roll over, it will stop after one or two rolls instead of falling off your notes.
2) Improved storage capacity.
In my experience I have found that around 4GB is enough to record an entire year's worth of lectures, so 8GB might seem a bit excessive at first. However, Livescribe has steadily been launching more applications for their smartpens. One might argue that the space can be used for applications (some of which can reach a considerable size, such as the English dictionary currently available) so if you plan on using a lot of apps it's best to go with the Echo.
3) Docking cradle replaced with standard USB cable.
The two main advantages to this are that you can buy a replacement cable fairly easily if your original one gets lost or damaged, and that the pen can be used while still connected to the PC. Livescribe have hinted at the future possibility that the pen will be able to be used as a graphics tablet because of this (possibly for an additional price).
4) A cap to cover the Infrared camera and ink tip.
A useful feature if you do not plan on getting a carrying case
for your Echo. Otherwise a fairly useless feature.
5) A rubber grip in the bottom half of the pen.
This pen does feel somewhat more comfortable to write with than the Pulse, but not dramatically so.
Apart from these improvements on the smartpen design, there are some thing which potential buyers should be aware of:
1) The Echo is larger (physically) than the Pulse. This gives it a tendency to stand out more, as well as making it just a bit more uncomfortable to carry. It also means that the Echo will not fit into the leather case that came with Pulse.
2) The Echo does not come with its own case, headphones or A4 notebook; all these things must be bought separately. It does come with a small A5 notebook though. Moreover, the Pulse's headphones will not work with the Echo smartpen.
3) Something rather minor, but the top half of the pen has been made out of a shiny plastic which easily smudges.
The bottom line is that if you are considering buying a smartpen for the first time, then go for the Echo. It really does do everything it is advertised to do and does it well. Moreover you are ensuring that you will be compatible with all future updates (such as the tablet functionality mentioned earlier).
If however you are considering an upgrade from a Pulse to an Echo, I would reccomend you wait either until your current smartpen definitely needs replacing (i.e. breaks) or you really feel you cannot live without one of the features/improvements mentioned above.
EDIT: One thing I forgot to mention in my initial review is the brilliant customer service Livescribe have. You can get in touch with them quite easily and so far they've always sent a personalized reply to my queries.