I've done 4 MS Certs now and I tend to complete them in around 45 - 60 mins, there are between 40 and 50 multiple choice questions and you need to go to a Microsoft Certified training centre to complete them. They are not web based.
I largely feel MS Certs are worth it if not to go over material that you might not come across in your day to day job. But it also give you more credibility to a certain extent against someone who hasn't bothered to do any at all. In fact I see no reason why any serious MS developer shouldn't be constantly taking exams.
I'm a bit of a hypocrite because its been ages since my last one, but I have a SharePoint 2010 one coming up in a couple of weeks and I really haven't done enough revision.
I find 90% of the training material to be utterly boring to read and alot of the questions on the tests are obscure and stuff you would likely never want to know again.
Can't you just buy them?
I get emails all the time offering me authentic certifications and degrees for anything I want from my choice of school etc... I was thinking of buying degrees for a rocket scientist, or a brain surgeon, just to hang on the wall.
I'd rather spend my money on Russian brides and Viagra
ontopic: The certs are crucial for a company - they net you partner points and qualify you to a big discount on the msdn subscriptions.
That was the only reason I did the certifications and the only time I've ever used them. Besides those points they are rather useless - I've never used them, no one ever asked about them (I just looked them on the partner website, I didn't even remember what topics I did)
From the learning perspective I had mixed feelings - as some of the questions were weird/useless, as they required a knowledge of a specific api, in a sense where the wrong answer would have been caught by the compiler, you'd normally use intellisense or hit F1.
So if you're in it for the learning experience, I'd recommend staying away from the learning material and the tests. If you fancy .net/c# pick up Jeffrey Richters excellent book clr via c# or channel9 screencasts or opensource projects or... well anything but the certification stuff.
If you need to use computerized tests to gauge development skills I'd pose a problem, and let them solve it. Compile it on back end and run it against some inputs like pex for fun or http://codility.com/
I mean, c'mon they're ms!
oh, btw: The tests are done in a testing center and are multiple choice.