I just took 70-228 and failed it. This is the 5th MS exam I've taken, and the first one I failed. I don't have experience with SQL Server, so I spent more time studying for this test than for any other -- about 6 weeks. I used Self Test Software and the 700-page book by Osborne/Syngress.
Self Test Software is normally good stuff, but it didn't prepare me for this, and forget about the Osborne book. The largest chapter was about replication, and there wasn't a single question about replication on the test.
Meanwhile, there was a bunch of questions where they give you a page of reading, plus a big exhibit showing the database schema, plus another big exhibit showing all the indexes, and then you have to analyze it and figure out how to improve the query time. Neither STS nor the Osborne book prepared me for these sorts of questions.