As an attempt to create a 'Holmes type' character suitable for D20, this works well. The character has a number of new abilities ideally suited for detective work. From being able to deduce facts merely through observation, to being able to predict the behaviour of a known criminal, the Scientific Detective would have numerous advantages during an investigation. Concentrating on such situations, the detective is less able in other activities, and as such is unlikely to unbalance a well planned game.
On the downside, it would be useful, though not essential, if the pdf included scenario ideas, pre-generated character examples, advice on fitting the character into a campaign, and so on.
Overall: An interesting and well thought out character concept. Additonal material would be nice, but isn't vital.
[4 of 5 Stars!]