Ruger P-series have no real weaknesses
But they lack some strengths that some higher class guns have.
As an example, they are not finished as well as Berettas and HKs. The recoil is not as soft as an HK USP9. The trigger's not as good. It's not as German. (OK, that last one was a jest)
My P90 was accurate and reliable, but the trigger was just OK. It was also very bulky in the slide for a single stack. It was my second gun, and I kept it from 1997, when I bought it brand new as a 21 year old until a couple years ago, when I sold it and replaced it with an SP-101. (I think that's where the money went...)
But you're right, it was a great gun.
I don't think it is that folks don't
like them. I think it is more like they don't get
passionate about them. They have a lot of the same virtues and vices as Glocks do, but at a fairer price, and made in the USA.
I probably shouldn't have said that. Now you're going to be dreaming about HKs and cursing my name when you're all of a sudden not satisfied with the Ruger any more. I hope you have the strength to resist.
If you see someone at the range with an HK, see if you can give it a go. They're pretty amazing. After I shot one, I understood how they can still sell guns at those high prices. (no, I don't even have one!)