As others have mentioned, if it's inferior it means it doesn't function better... therefor making the thing it's being compared to superior.
The only thing that comes to mind right now is the durability and longevity of "smart" phones. While phones on a whole have become closer to computers then the phone you have hanging on your wall or sitting on your desk, I remember having an old chunky nokia mobile (cell phone for ye yanks) and that thing lasted YEARS. Like nearly a decade. In fact, it still works, it's just nobody uses it anymore except for instances where the newer phones break.
Which comes to the main issue. Those fancy slim phones with all their utility and functionality... they break really easy. Not just from falls and water damage (though they are really fragile), but from software related issues. I've had a few phones that broke themselves during a firmware updates. Granted it just required a wipe to sort out and it was just a massive inconvenience, but it's still an inferior quality compared to the older more stable phones.
Obviously this gets better over the years as the tech becomes more refined, but growing pains are still noticeable sometimes.
They don't last as long either. They can (and have done for me) get bricked within 4 years or so, if any of the common phone related incidents doesn't do it in first. Not sure what causes it but I think it's hardware damage resulting from the heat that comes from the battery (they can get surprisingly hot, which is why I don't like to leave it in pockets close to my vitals). It really does feel like a "they don't build it like they used to" scenario. I mean, I'm really careful with my phones and have great respect for the tech (unlike my sister who goes trough phones like toilet paper), but even when I'm really careful they can just up and die on me.
Other then that, I can't imagine living without a smart, touchscreen phone with all the fancy apps in today's world. I like being reminded that our technology is, in some cases, more advanced then the tech in Star Trek.