Took 290 and 291 this today
For those of you who are interested, I'll try to give a decent summary of what I discovered about these two exams.
70-290 was really pretty simple. Basically cover the objectives and you should be fine. The SIMS were very easy, but I think they were also a good measure of ability. My score was 900.
70-291 was considerably more difficult (my score where was 884). First let me say, that even though I've heard several of you call it "The Beast", it's still not as hard as the true original Beast (70-216). Now before the arguments come, let me explain why I say that. First of all, some of the DNS, RRAS, and DHCP stuff was the same. The major difference is with the SIMS and more interactive type questions, you get to demonstrate your knowledge based on doing it exactly like you would in preparing for the exam or as you would in the real world. With 216 there were NO sims, so instead of "Configure this zone to be active directory integrated and accept only secure dynamic updates" you got "which answer outlines the correct steps for configuring this zone to be active directory integrated and to support only secure dynamic updates" followed by explanations that sounded very much alike except for maybe the name of the tab being mixed up. On the sims on 291, if you don't remember exactly which tab, that's fine, just click a couple of em until you find the one you're looking for. And also, I have to confess 216 is the only MS exam I've ever had to take twice to pass.
Now let me explain the things that make this exam difficult and for whom it will be most difficult for. If you're good with the theory and don't pay attention to detail when configuring things (MX records, pointer records, zones, zone transfers, RRAS, etc.) then you will surely have an extremely difficult time. Also the wording in some cases seems to be a little more difficult on 291; in other words I think they're saying no one should hold your hand and have to tell you every detail of what you need to configure. For example, the sim question might read "Create and configure a group policy for the Marketing OU that will prevent users from making changes to internet privacy settings and force a minimum password length of 10 characters, also the Accounting department corporate security policy requires a smart card for logon for all all computers in the Accounting OU" usually with a few more trivial tasks added. Then the end of the question might say something like "perform the needed operations by applying the minimum amount of GPO's." So this makes the questions seemingly more difficult because you have to know why you're doing what you're doing. However the fact that you're doing it sims again makes it easier than trying to remember all the steps and the order of them versus just doing it. All said and done, I stand by my statement of 216 being more difficult and still deserving of the title "The Beast", however I think 291 is a much more honest test and does a much better job of proving your compentency in the given area.
But the underlying gothcha of 291 is that you'll usually have anywhere from 3 to 7 sims (I had 5 and have known a couple of people to get 7) and the rest will be multiple choice, drag and drop and other interactive questions styles. And we all know how wordy Microsoft's multiple choice questions can be, so be prepared to use at least 3 hours of the 4 hour time limit. And concerning DNS? Business as usual, no less than half my test was either DNS or at least related to DNS in some way. And the surprise part? There were quiet a few security related questions, so if you're a person who's kinda skated by and never really understood what those darn security template things were for and how to properly apply them, look out. Also the routing questions were a little more advanced than on 216. The simple questions which show you a tcp/ip configuration with an obviously wrong default gateway address are pretty much going away.
Good luck to all who's preparing for these exams. My advice would be to print yourself a copy of all the objectives, set up a lab, then go through and install, setup, configure, and reconfigure every technology in the objectives. Do this three or four times for each and you should be okay. And always remember, if you're very week in area, then the exam crams and test prep books will not give you what you need. Google, ask questions on here etc. Until you completely understand the concepts.
Good luck to all and I hope this helps some of you.
Keatron