In my experience with the polygonal lasso tool and it's kin, I've found that the tool can work well provided you've adequate experience with it, but even an assload of experience with it will rarely give you the results you wish for. Even if you end up doing a decent job, you're still left with a good while of time to spend cleaning up and reconstructing the areas you screwed up on. It's archaic, simply put.
A little over a year ago, I had finally come to the point where I couldn't be assed to struggle with the tool any longer and so I sought to find alternative methods for extraction. In doing so, I ended up coming across
Shinta's pen tool tutorial (click) and after some practice I got the hang of it. Before hand, I - and others, judging by what I've read from members here on AO's previous incarnate - were confuzzled by the tool, and even somewhat imitated. Working with paths just seemed to complex to a n00b graphic designer. But after toying around with it a bit, I came to the conclusion that it's superior; that is, for me at least.
With the polygonal lasso, the your end product is as is, every mistake is left to you to fix by other means, unless you care to spend another three hours or so on a mulligan. Of course, if you find a bigger scan and want
that copy extracted, you'll have to do it all over again, anyway (go right ahead and take a small extraction, resize it upwards to fit the dimensions of a larger version of your image, and extract the larger image using the load selection feature; looks terrible, no?). With the pen tool, you can convert your work path into a vector shape should you come across a larger version of the image you're working on in the future. Oh yeah, you can save your paths, so if there's anything you want to go back and redo, you can simply select the path and make the necessary adjustments via the convert point / add anchor / delete anchor tools. Moreover, should you choose to forego that editing method, you can use a one pixel path stroke to create a uniform outline masking unsightly artifacts left over.
Oh, and did I mention the pen tool is quicker? With the polygonal lasso, I'd waste away some three to four hours working at 800% zoom. In contrast, I spend usually an hour to two hours working at various zooms from 200% to 500%.
Personally, I think it's immensely better.
As far as image cleaning goes, I use a combination of the clone stamp tool, the blur tool, the smudge tool, the eyedropper tool, the pen tool, the dodge and burn tools, and the brush tool. Filters usually can't do all the work for you, but they can help.