On the one hand this question has been asked to death on the internet (and yuttadhammo's videos even try to handle it). On the other hand, I personally still don't feel I have a clear answer (and I don't think that's because I'm an idiot.)

From my overall reading, the commonest answer seems to be that while the primary aim in meditation is insight, it is not only useful, but advisable (and maybe even essential) that one first achieves some degree of tranquility or quiescence before moving on to insight. Specifically, it is advised that one attain at least access concentration, if not full-blown first jhana, before moving to insight work.

However, there appears to be an important exception to that rule, coming from (at least) the Mahasi tradition, wherein the idea of "bare insight" arises.

From the existence of those apparently different positions, I am confused in two ways.

First: if the bare insight thing is valid -- i.e. if it is possible to go straight to Vipassana without going via Samatha -- then why wouldn't everyone just do that? Insight is The Point, after all, (isn't it?) so why waste time with what seems to be mere training wheels?

Second: OK, suppose access concentration or first jhana is necessary, but is also sufficient a level of samadhi as preparation for vipassana. Then, again, why would anyone then continue on to "samatha" jhanas 2 through 4? My understanding is that while those jhanas may be cool and blissful, not only are they not The Point, they carry the danger of attachment. So why bother with them?

To pre-empt any "it doesn't matter" style answers, I really think it does. There are several apparently good teachers out there whose approach is, to paraphrase, "No, don't note yet. We're not doing that until we've got a bit of focus", while there are others who get you noting from day one. So overall it may not matter, but it matters to beginners (like me) as part of deciding on a teacher (and on how to meditate while I look for a teacher).