Thanks for your question, which is currently on my mind also (it is one of the reasons I joined this forum about a week ago). Very thoughtful and helpful replies so far, let me throw in my $.02 as my first post.
My 70 year old father-in-law, who does not use computers, is a subscriber to the Wiener Newsletter and has used it as just one of his guides for the past couple of years of successful investing [i.e. during the recently ended bull market]. He lent me his copies of the Dec 2007 through April 2008 newsletters last week.
As a newbie investor - I've been passively investing in S+P 500 Index funds for about a decade, but recently decided to learn more by reading Bogle and others - here are my opinions/impressions on the Weiner newsletter, based on those five recent issues :
Out of the 16 pages, about 4-5 are performance charts for all Vanguard funds (information available elsewhere for free) and one page for the example Wiener portfolios. Each newsletter also has a couple blurbs promoting DW and what he is selling or where he is speaking.
Each newsletter has an "interview" with a Vanguard Fund manager or other investment figure in a style which I would describe as fawning. There are usually two cover articles on what DW thinks is going on in the financial world; or articles on general topics like IRAs, etc., which are better written - but also information available elsewhere, often for free.
In addition to promoting his diversified portfolios [with, as noted already, sometimes unavailable closed funds], DW promotes "Hot Hands" funds which are actively managed funds which have performed well in the recent past. This strategy is called momentum investing. I am currently reading "A Random Walk Down Wall Street", by Professor Burton Malkiel, which is very critical of this strategy [and many others].
I am sure that the fans of DW here can provide you with some other titles to back him up!
Along with what I consider an ingratiating style, DW does not appear to be consistent to me. He downplays his misses while trumpeting how clever "you and I" are when he is successful. In the Feb 2008 newsletter he cited Grantham, Mayo, Van Otterloo, one of the outside fund management companies used by Vanguard, in his defense of his "Hot hands" strategy, only to report in the very next newsletter that GMO got fired by Vanguard.
Based on the almost half year's worth of newsletters I have read, my advice to you is to
1) Use Morningstar for fund research,
2) Spend your money on some of the excellent books on investing recommended here. I have recently bought a half dozen of the most recommended (Bogle on mutual funds, Bernstein on allocation, Bogleheads guide, Morningstar books, etc.) for under $99.
3) Ask questions and read the educational posts on here.
4) One of my next projects is to research the Morningstar Vanguard Family Funds newsletter. (I have not yet tried searching for opinions of that here, does anyone care to bite the hand that feeds us?) ;-)