There is nothing wrong with the UHFS and anyone that has compared it to the standard system and walked away thinking the two are even remotely similar in performance probably went into the comparison with a little confirmation bias or doesn't listen to their music very loud. And that's fine. For those people the standard system might suffice however, objectively it is one of the worst systems I've heard in any car, let alone a luxury car. It has no discernible bass, it distorts at moderate volume levels and just generally sounds bad. It's good for talk radio.
I can appreciate a good system. I love music and I love listening to it at a higher volume. Few things beat a system that can deliver hard, clear bass and good clarity at higher volumes. I have car ADD and swap vehicles a lot. Because of that, I've had a bunch of the higher end systems in the past 3 - 4 years. Here's what I've had in order of how good it's been.
5. Audi A8/ Infiniti Q45 Bose Systems - Good clarity, good bass but muddy, suffered in the highs. Overall good entry level systems for luxury cars. I should add that Bose makes systems of all varying qualities. I assume the manufacturer gives them a budget and they build a system around that budget. So Bose might be utter crap on one car and very good on another. They don't seem to be like the true premium brands that will only license their name to quality systems. Bose will happily slap their name on garbage. Don't believe me? Go find a 2000 Grand Prix with a Bose system... :-D
4. BMW E60 M5/ 550/ 535 Harmon Kardon Logic 7 - Amazing clarity, very clear bass, very strong mid-range. This system's shortcoming was that it did a poor job of modulating bass. At low volumes you were constantly forced to lower the bass because the subwoofers would over-power everything. For the $850 BMW charged for this system is was a bargain.
3. Audi A8 Bang & Olufsen - This was a 2007 A8. This system was incredibly clear but lacked bass. I believe Audi used rear shelf mounted subwoofers which is no bueno. It's frustrating listening to a system like this because it's so incredibly clear at high volumes but you feel like someone dialed down the bass knob by half. Still, clarity was stunning and who doesn't like a motorized tweeter shooting out of their dash?
2. Tesla UHFS - Yes, that's right, this is number 2 on my list. The system is solidly good. Bass is strong, highs aren't tinny and the system is clear right up until max volume. If I have to nitpick, I'd say the mid-range bass doesn't hit as hard as the BMW system but that's a product of what appears to be a bandpass subwoofer box the Tesla system uses versus BMW's dual in floor sealed drivers.
1. BMW 535D Bang & Olufsen - Basically everything awesome about the A8's system but they finally fixed the missing bass. I know people like to say B&O is gimmicky but that system was amazing. I haven't heard anything close to it.
So in my opinion the UHFS is not only in good company but near the top of the heap in good company. I'd pay $2500 for this system all day every day. If it's not for some people, I get that. Not everyone cares about sound but if you do care and you walk out not being able to hear a difference between the two systems do yourself a favor and go back and try again because while some of this admittedly comes down to preference and opinion, distortion and lack of bass are not objective and they are very much present on the standard system at even moderate volume levels.
Lastly, two things of note when testing these systems:
1. High end systems generally sound worse with standard audio sources. XM radio on the B&O systems was embarrassingly bad to the point where I wondered why BMW/ Audi offered it as an option. The reason for this is that higher end systems more accurately represent any given frequency range and thus expose compression artifacts that a lesser system might hide. People assume satellite radio is high quality. It's actually highly compressed trash.
2. Most people don't crank the volume in the showroom or with a salesman. Likewise, in a quite showroom or in a parked car your threshold for what you consider loud is much lower than when you're driving and there is noise outside the vehicle, road noise, wind noise, etc. Half the time I get back in my Model S I'm reminded of this as my ears are acclimated to silence but my volume in the car is set at where it was when I left it. That initially seems very loud.