Personally, I like having a desktop and laptop, but if money is very tight and you would benefit greatly from having a new mobile computer, just getting a MBP is one option.
However, given that new iMacs are expected imminently, there might be some nice new features worth having sure youre away of it, but I think some of the advice youve been given doesnt reflect that.
As to the MB itself
As to the issues with the MB, the main known issues seem to affect older revisions for example, because of the discolouration problem Apple has changed the plastic in the palm rest. Obviously, with the MBs only recently updated, you could argue that its too early to tell that this latest revision will have absolutely new problems however, as the MB is now a mature product, I think you can buy with confidence as known problems will inevitably get fixed as the product matures. Of course, there are issues with the current MBPs which is only to be expected in a not exactly minor update but certainly nothing to the extent that you should decide against buying.
Its very easy to overestimate product problems in forums (as Scarlet Fever says), and youre best off going to a site with editorial control like Macintouch or Macfixit to get more sober information. Incidentally, in a survey Macintouch did at the end of 2006, out of 3,000 laptops, it found that the 17 MBP was most reliable, followed by the MB and then the 15 MBP. With the latter, it tended to be because of a logic board problem, which Apple obviously fixed Im not saying that this made the 15 to be an inferior product or that Macintouchs findings was 100% representative, but its a decent example to show spending more money is never a guarantee of trouble-free computing, despite what some posters say in many a thread.
As I say, when it comes to the MB, you can buy with (reasonable) confidence now but do have a look at Macintouch, its a useful resource and you can pick up some good tips.