Excellent, indeed! Loved the visuals and the feel of the mansion, as well as the basement and related areas! Perfect level of difficulty for the 'early' guards, a bit annoying just how reactive the 'later' guards were (almost unrealistically so, compared to the 'early' ones). Would be 'excellent' for all catagories, if such a poll had been included in this thread!
As per the grates:
A few things to perhaps fix, but aren't a complaint so much as a polishing-up of such an excellent effort - as someone else commented earlier most of the moveables aren't placed correctly (1 pixel above the item they are one) and so fall 'into' the object below (this happened dozens of times to me, and so became the only immersion-breaking aspect). There are a few lamps hung from a chain, and as can be seen if climbing onto the roof of the stable the chains stick up thru into the open air - happens inside the mansion in at least one place as well. And as noted above, the 'later' guards are overly sensitive to sounds, even ones made while creeping across tile in deepest shadows.
The way the loot was findable is quite logical and realistic -
If you finish more of your missions, I look forward to playing them too!