Thirty-two days ago, I purchased Apple’s iPad, after proclaiming that I wouldn’t. A gadget like this one should be tested if repeatedly blogged about. I would have used a for-reviews loaner, but I’m on the same fraked list as Gizmodo. I bought my own. A month-or-so usage later, I agree with Tumblr and Instapaper developer Marco Arment, who asked about iPad yesterday: “What’s it for, really? Logically, it doesn’t make a lot of sense for most computer owners…most people will have trouble justifying the $500 entry price.”

My problem is similar to Arment’s: I like the iPad, but can’t find a use for it. The tablet is too big to replace a cell phone and it’s not functional enough to displace my laptop. I would never buy the butt-ugly Amazon Kindle or slow-as-cold-molasses Barnes and Noble Nook, yet I find iPad to be a so-so satisfactory substitute e-book reader. I managed to reread Orson Scott Card’s excellent Ender’s Game and am trudging through sequel Speaker for the Dead. But it’s reading for convenience, not joy.

“A gadget just needs to be good at something that you need or want to do,” Arment writes. Yeah exactly. He has found a few good-at-somethings, but I assert nothing that he couldn’t do as well — or better — on a laptop. “It’s the perfect living-room computer that lives on the coffee table and can be used to quickly look up a fact, find a restaurant, check mail, browse news, and play a game,” he asserts. So is my smartphone, which doesn’t cost $499 to $829.

The personal computer succeeded in part because it is versatile, multi-use, all-purpose device. The PC does many things fairly well. Ubiquity is why the PC is ubiquitous. But as I predicted, Apple’s tablet isn’t really good enough to replace PC or smartphone. Arment writes:

Accepting that the iPad isn’t an all-purpose computing device is going to be a slow process for everyone, including Apple. They can’t quite explain what it’s for, either, which is why the launch marketing, software, and accessories are a bit scatterbrained. For instance, if you’re using a hardware keyboard with the iPad very often, you’d probably be much better served by a MacBook Air.

So what is iPad good for then? Arment and I agree on something else. But in iPad’s defense, I explained: “There also is UX, or user experience, which is as much emotive as it is functional…iPhone is more a joy to use [than Google Nexus One]. There’s something about UI design and tactile, responsiveness of the screen that make me feel good. I can say the same about using iPad.”

Arment describes using iPad as “satisfying and delightful.” I totally agree. It’s the main reason I have resisted selling mine. Functionally, my iPad isn’t good enough at anything to justifying keeping it. But emotionally, I’m hooked. I find parting with iPad to be difficult. Sitting down to use the tablet, I suddenly get girlie giggly. It’s a happy experience. If you asked me why, I would say it has something to do with the the user interface’s beauty and how it responds to my touch. But that kind of intellectual evaluation just doesn’t nail down why.

Yesterday, Nokia’s Joe Gallo tweeted: “Can anyone explain to me why this video is funny” Gallo referred to YouTube video “Charlie bit my finger — again!,” which has 191,352,797 views, as I write. I resisted laughing but couldn’t stop on second viewing. “By that last tweet, I meant, I was cracking up and had no idea why!” Gallo later tweeted. In assessing my response to iPad, I have similar reaction. I can’t put my finger on why (no pun intended) using iPad makes me happy.

There are lots worse reasons for using a product than it makes you happy, and many product designers would kill to have that kind of customer problem. “Ah, our product gives you joy even though you can’t fathom a use for it, and you’re going to keep it even though you’ve got no use for it?”

I’ll use iPad for awhile longer to test the apps and to see whether this happy thing wears off. I’ve already had several good offers to buy the Apple tablet. But my answers have been nos. Functionally, iPad isn’t for everyone, and it’s probably not for most people. Too many features overlap the smartphone below and laptop above. Nevertheless, here’s a question for potential buyers: How much joy can you get for $500 — iPad’s starting price? Stated another way, how much joy is worth spending $500?

I giggle every time I turn the damn thing on. Who knows? Maybe someday I’ll find a real use for iPad. For now, a little joy is reason enough.