Some of the more basic chapters will be very useful for anyone, but other chapters are pretty heavy going. A degree in something biological is probably required to understand it all, even then some bits (daylength vs temperature in garlic - aargh!) take several readings.

It is clearly written, my main criticism is that it deals mostly with just onions, garlic and leeks, as they are what are grown commercially. Other unusual alliums (which I am more interested in) get much less mention (I guess there's just less known about them), often being referred to in passing only.

An interesting alternative to consider is Plants for a Future (ISBN: 1856230112), a wonderful book by Ken Fern, covering a whole range of interesting edible plants. This is from the other end of the spectrum, aimed at the keen home/permaculture grower, but is just as useful in many ways. There is a lot abut alliums in there because he's personally keen on them - he does cover many of the unusual alliums, often with tasting & growing notes based on personal experience in the UK.