EDIT: After buying a neo smartpen and using it for 6 months or so I have a few more comments. First, the smartpen eventually broke like every other one I've ever owned so if you aren't super careful with your pens be on guard. Secondly, it just wasn't worth the trouble. None of the software accurately transcribes math symbols, the tagging and searching systems suck for math so at the end of the day I just paid more than a hundred bucks for a system which was about as good as just photographing my pages with my cellphone once I write them. I was a big fan of this idea so it's too bad but I'm going to try one of those digital pads for drawing next.
I used to use a livescribe pen years ago (perhaps an echo) and it wasn't very convenient. The biggest problem at that time was that handwriting recognition was utterly terrible and thus the resulting notes were completely unsearchable and there was no real convenient way to synchronize in a way that didn't perfectly match up with the notebooks (if I accidentally did work on Martin-Lof randoms in the notebook for REA sets I couldn't move those two pages over to the appropriate place in a way that didn't get messed up on next sync). Not to mention the app sucked. However, both the actual writing capture and the audio capture worked quite well.
My conclusion was that for me it was more a way to make my research notebooks extra cool and special and it wasn't actually useful but that had I been the sort of person who took notes at talks or classes and went back to look at them it would have been mildly useful and could have been super useful with better handwriting recognition. A pen which combined handwriting recognition with some kind of latex recognition engine would have been very useful.
I'm thinking of buying another smart pen now that the tech has had some time to mature and my advice to anyone else considering this is make your buying choice based on the app, third party tools/api, notebooks/printable paper and pen quality rather than the pen tech. At least assuming it has basic functionality.
Note that after doing a bit more research I see that livescribe hasn't changed or even doubled down on many of the things I found frustrating about their system. Their notebooks might be fine for taking notes in class but I want something that's both nicer and full sized for my research and the best they can do is their executive notebook which is both unimpressive and comes in only two colors. To be fair to livescribe their pens seem better equipped (memory) to record audio but I don't use that feature. Also they support export directly to onenote (as pdfs) but only seem to support auto-sync to evernote and even there you seem to need to tap sync.
Worse, rather than fix the issues with their API they've removed developer access entirely and (though I haven't fully checked this). I'd like a smartpen which I can at least dream of having math recognition added.
OTOH I've been quite impressed with what I've seen of the neo smartpens. They may lack a mac desktop app but they have a published API on github, a very nice selection of notebooks, seem to support more options for exporting content (e.g. svg) syncing (auto google drive) and advertise the ability of their software to regroup pages in dynamic notebooks. I'm going to purchase one today and if anyone wants to know how it worked out comment on this answer to remind me to come back and update it.
Moleskin doesn't look bad either but my understanding is it's basically a neo smartpen underneath and I couldn't figure out from the website if it's fully compatible or you are stuck with a few (really nice!!) smart notebooks from moleskin and if it's not fully neo compatible I don't want to be locked in to such a boutique option.