Originally this product was launched in 1850 for the Austro-Hungarian Emperor, and it surely must have changed since then.
Initially there is a lemon note, with bergamot mixed in and quite dominant initially. Gentle freshness pervades.
The heart notes centred around a tonka sweetness, which again is very discreet. Certainly it is never intense of intrusive.
Then the sandalwood arrives. Sometimes states to be a Mysore Sandalwood (1), but it is very restrained and later in the bases is soon pushed aside by some ambergris - as it happen a bit in Creed's creations over the decades.
I get soft sillage, adequate projection and a decent longevity of about four hours.
This is not an intensive scent for warmer autumn days and great in the office. Santal Imperial is centered around a fairly straightforward sandalwood, which is less intense than Bois de Santal of the same House, and rather pale at times. A conservative, classic and unobtrusive yet quite convincing sandalwood fragrance, if one ignores the performance issues. 3.5/5
Ref: (1) https://www.fragrantica.com/perfume/Creed/Santal-Imperial-7513.html accessed 12 June 2020