Before you buy the ZTE Peel for your iPod Touch, keep in mind some of its limitations.

A couple weeks back I told you about the Sprint ZTE Peel, an iPod Touch accessory that sounded almost too good to be true. For a mere $79.99, plus a no-contract monthly service fee of $29.99, you could add 3G connectivity to your Touch.

Goodbye, pricey iPhone! Hello, much more affordable iPod Touch-Phone! Well, not quite. Now that I've had a chance to test-drive one, I must admit it's not what I expected. Here are five reasons why:

1. It's not actually a dock.

I mistakenly assumed that the Peel plugged into the Touch's dock connector, much like an external battery/case hybrid. But it doesn't: the Peel is actually a kind of specialized MiFi 2200, one that's been molded to function as an iPod Touch (second- or third-gen) case. Just pop in your device--or don't. Makes no difference.

2. Only two devices can access the Peel's connection.

Either the preliminary information was incorrect, or I made a mistake, but I originally wrote that two other devices could tap the Peel's 3G goodness at the same time as your Touch. In reality, it's two devices total. Again, it doesn't matter if your Touch is snapped into the enclosure or not--two devices, period. I wouldn't call that a deal breaker, but it's a little disappointing given that the MiFi supports up to five. On the other hand...

3. Performance bites.

Maybe the two-device limitation is due to the Peel's sub-3G connectivity. I tested it in several locales around my neck of the woods (metro Detroit), and according to Speed Test, the best download speed it could manage was 0.87 Mbps. Contrast that with my AT&'T-powered iPhone 4, which pulled 2.6 Mbps--in my basement. Your mileage will almost certainly vary, but the Peel proved pretty pokey. Is it better than nothing for the Wi-Fi-strapped iPod user Absolutely. But I'm discouraged that it doesn't come anywhere near Sprint's advertised 3G performance.

4. It relies on Micro-USB charging.

Yep, another power cord to bring along. Although Micro-USB is an increasingly popular standard, a dock connector would have made the Peel much easier to travel with. It also would have enabled you to sync your Touch without having to pop it out of the case.

5. It requires a headset adapter

The Peel's audio-jack pass-through is just a hair too deep and narrow to accommodate a stock pair of Apple earbuds, so you have to plug in a tiny adapter cord. Another thing to bring along, another thing to potentially lose. That's a pretty annoying design flaw.

Another annoyance: the included "Getting Started" guide doesn't tell you how do to things like set up a password so other users can't tap your mobile hot spot. You can find instructions on Sprint's Web site, but they're buried in the poorly titled "Admin Guide."

Furthermore, the Peel is bulky, making your otherwise slender device feel a lot more brick-like in your pocket. The good news is that it's reasonably light, adding just 2.6 ounces to an iPod Touch's travel weight.

I could forgive a lot of these issues--maybe even all of them--if Sprint didn't cap your monthly data at a paltry 1GB. If you go over, it'll cost you 5 cents per megabyte. To me that just seems stingy. A 2GB cap would make this whole enchilada a lot more appealing.

Even so, I think the Peel might just find its way into a few stockings this holiday season. Would you like to see one turn up in yours