It's really hard to say, considering that practically everything recorded about him seems to have been filtered through Paul at some stage. You can take a stab at it with the help of some pretty sophisticated textual analysis methods (I think the Jesus Seminar did a pretty good, though not unimpeachable, job of this), but ultimately an analysis always depends as much on readers' preconceptions as it does on the actual text. Kind of like trying to get an handle on Socrates' ideas when all we've got to base them on is Plato and a handful of contemporary commentaries -- except worse, since analogous commentaries don't exist in this case.
I'd lean toward "dissident rabbi" based on the charitable version of my reading of the New Testament, but readings of the New Testament are notoriously idiosyncratic for the same reasons.
A few notes about the site mechanics
A few notes about the community
If English is not your first language, don't let that make you afraid to post or comment. You can get English help on Discussion- or Main-level posts by sending a PM to one of the following users (use the "send message" link on the upper right of their user page). Either put the text of the post in the PM, or just say that you'd like English help and you'll get a response with an email address.
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A note for theists: you will find the Less Wrong community to be predominantly atheist, though not completely so, and most of us are genuinely respectful of religious people who keep the usual community norms. It's worth saying that we might think religion is off-topic in some places where you think it's on-topic, so be thoughtful about where and how you start explicitly talking about it; some of us are happy to talk about religion, some of us aren't interested. Bear in mind that many of us really, truly have given full consideration to theistic claims and found them to be false, so starting with the most common arguments is pretty likely just to annoy people. Anyhow, it's absolutely OK to mention that you're religious in your welcome post and to invite a discussion there.
A list of some posts that are pretty awesome
I recommend the major sequences to everybody, but I realize how daunting they look at first. So for purposes of immediate gratification, the following posts are particularly interesting/illuminating/provocative and don't require any previous reading:
More suggestions are welcome! Or just check out the top-rated posts from the history of Less Wrong. Most posts at +50 or more are well worth your time.
Welcome to Less Wrong, and we look forward to hearing from you throughout the site.
(Note from orthonormal: MBlume and other contributors wrote the original version of this welcome message, and I've stolen heavily from it.)