If you are a dyed-in-the-wool passive indexer, Paul Merriman's "Financial Fitness Forever" is a much better book overall. Both Merriman and Solin reach the same basic "ultimate" portfolios - not surprising since they both start with Fama and French's academic work. I find Paul's writing to be more informative and less snarky. Paul also uses longer timeframes to evaluate portfolio performance, which is essential to getting a feel for how a portfolio works in other investing environments. Paul goes back to Jan 1970 for his portfolio development. Solin goes back to 1990, which I find statistically insignificant since it doesn't include the inflation and bad markets of the 70's. Merriman does a much better job showing how he develops his top portfolios and even shows investors in Fidelity, Vanguard, TR Price which specific funds to use in establishing his ultimate portfolio for their accounts. And he even goes one step further by showing employees of 50 top companies how to invest their IRA fund choices to best match is top portfolio. Merriman's book outperforms Solin's by a wide margin.
On the other hand, if you are a new investor, an open-minded and inquisitive investor, or if you were a passive investor who got totally burned by the false promises of 'diversification of a long-only portfolio' mantra, the best book I have read in a very long time is called "Jackass Investing: Don't Do It, Profit From It". The author takes aim at the 20 big investing myths (hint: "Buy and Hold works well for Long Term Investors", "You Can't Time the Market", and "Passive Investing Beats Active Investing" are 3 of the first 4 myths) and does a superb job of explaining, in clear language and easy to understand examples, why each of these are just plain wrong.
I highly recommend reading the "Jackass Investing" book before deciding on how to invest your money. Even if you don't agree with the author, I guarantee that you will have a new appreciation for just how tenuous the foundation is under the "passive investing with long-only index funds" mantra and why you may not want to tie your retirement to this leaky boat. As the author of Jackass Investing so comically states, 'Buy and hold is really not a "strategy" at all, but merely a way to rationalize losses'.
Also, Mr Solin is an example of someone who will make money off investors by convincing them they have no hope of ever learning how to invest their money successfully, and his company will pocket anywhere from .5 to 1% of your assets per year giving you access to the vaunted (and overhyped) DFA funds. Imagine your $1M portfolio providing Mr Solin and his company $5k to $10k/yr for doing virtually nothing to manage your money. And if your portfolio is down 15% (like it might have been in 2008), his company will still get $5k to $10k for that year. Wow, nice gig you have, Mr Solin! Ironic that he disses others in the financial industry.
My suggestions on where to learn how to invest successfully: Bill O'Neil and Michael Covel. They each have proven systems that work, and there is overwhelming evidence from the large number of people succeeding with those systems to disprove much of what Mr Solin talks about in his book. Yes, it takes time and effort, but your successful retirement depends on learning how to manage your money and earning an acceptable absolute return every year. Being a passive index investor and losing 15% to 20% in 2008 (like I know some DFA portfolios did), or having to wait 3 to 5 years for your account to rebound isn't the path to success, at least not for me. Read Covel's books to see how trend followers actually made good money in 2008, and will continue to make money in up or down markets.