Thus I conclude one cannot take Improved Sense: Ultrasound. Thoughts?
No offense, but your quote is incomplete and therefore misleading. Unintentionally I presume. The relevant passages should include:
This power gives you sensory improvements not normally possessed by your character’s metatype. These improvements may include low-light or thermographic vision, high or low frequency hearing, and so on. Any sense enhancement provided by cyberware or bioware can be provided by this power, unless that enhancement either gives you bonus dice to Perception Tests or needs wireless to work (or both). In addition to the sensory enhancements listed for cyberware and bioware, other improvements that can be selected include:
P. 310 Core
The term improvement is really peripheral because everything provided by magic, bioware or cyberware that is "not normaly possessed by your character's metatype" is an improvement by definition.
The actual problem here is the distinction between the terms "sensory" and "sense". In the gear section, sensor refers to a subsection of devices that includes ultrasound, while sense, in it's traditional dictionary definition, is limited to the five human senses: sight, hearing, taste, smell and tactile sense. How the power works depends on a simple question: Is the use of the term sensory an intentional statement to extend the scope of the traditional five senses?
There are reasons for and against this:
1. Pro: The word sense could be used just as elegantly and easily. Rewriting the paragraph with sense instead of sensory makes for well formed english.
2. Pro: The power specifically mentions exceptions that are not present in bio and cyberware, making those seem all inclusive. (weak)
3. Contra: The use of sensory is not consistent.
4. Contra: Sensors in the equipment section is actually an umbrella term for devices that make use of "senses" (for want of a better term). This is a problematic point because this understanding of sensor defines ultrasound as a "sense".
Long story short, the RAW is very ambiguous and I think neither case is particularly strong. RAI on the other Hand makes a case for ultrasound to be acceptable though, in the simple fact that adepts already have a major incentive to go for augmentations for senses because they are that much cheaper. Getting just the simple Thermo & Low Light package with magic costs you as much as fully tricked out cybereyes. (Essence wise) You do sacrifice a magic point but I think we can all agree that it is worth it for most adepts to do so in general. Placing gadgets like ultrasound behind a semantic barrier makes little sense to me when 'ware is already so attractive.
Ultrasound gives away your position to every other ultrasound device in the area and is relatively easily interfered with because the "sound" bounces of everything, including normaly transparent surfaces. Despite what Splinter Cell (and other media) would have us believe, ultrasound does not allow you to see through walls. It's ability to detect invisibility can be gotten via astral perception, watchers and spirits and none of those can be replaced with it entirely, not to mention a simple Perception + Intuition [Mental] [Spellcasting - Force] test (Noticing Magic P. 280 Core). For the mundane, a handheld ultrasound sensor costs all of 100¥ and is available legally in every electronics store. It can be controlled wirelessly and connected to a comlink or trodes to be displayed via AR, so it doesn't even take a hand.
At the end of the day, Ultrasound is a very nice sense, but it's basically a combined low-light + thermographic vision with a range limit of 50 meters. Depending on your game, this may be a severe limitation or not. In mine it is a major one. Personally I think it's worth the 0,25PP but nowhere near overpowered. I'm currently playing a mystic adept that has the sense and so far it has only been used to negate flashpacks. While it's great for distances and "mapping" it's really bad at making minute distinctions between say, a statue and a person. Frankly, as long as it's played the way it's written and not the splinter cell "look through walls" way, it is useful but not more.