Early reviews of the Verizon iPhone were clear about one point: it’s a great phone, but data is slower than AT&T’s network. The Verizon iPhone gathered good phone call points among reviewers, but each one of them mentioned the fact that, both in download and upload, AT&T was faster. And it looks like things are only getting worse.

As reported by BGR, to handle the flock of new iPhone users on its network Verizon will begin throttling data speeds for the top 5% data users:

Verizon Wireless strives to provide customers the best experience when using our network, a shared resource among tens of millions of customers. To help achieve this, if you use an extraordinary amount of data and fall within the top 5% of Verizon Wireless data users we may reduce your data throughput speeds periodically for the remainder of your then current and immediately following billing cycle to ensure high quality network performance for other users at locations and times of peak demand.

But it gets even worse than data throttling. To keep its network capacity at an optimal level for customers, Verizon will compress images and videos over the air (to save bandwidth) before they’re served to a device. Here’s what the PDF memo says:

These techniques include caching less data, using less capacity, and sizing the video more appropriately for the device. The optimization process is agnostic to the content itself and to the website that provides it. While we invest much effort to avoid changing text, image, and video files in the compression process and while any change to the file is likely to be indiscernible, the optimization process may minimally impact the appearance of the file as displayed on your device.

While it’s likely that these “optimizations” (we think “compressions” is a more appropriate term) will happen only during the first period of Verizon iPhone on sale, it’s still inconvenient for customers to not have access to high-quality media on 3G. Full excerpts and link to the PDF document available on BGR. Pre-orders of the Verizon iPhone went live last night.

It begins. The usual TechCrunch, Walt Mossberg and Engadget got their Verizon iPhone units and have just posted reviews online. A few interesting quotes about sound and call quality:

Mossberg:

Calls on the Verizon unit were mostly crisp and clear, including speakerphone calls and those made over my car’s Bluetooth connection. On my first full day of testing, I did have several Verizon calls that dropped out for a few seconds, before recovering. Apple attributed this to a very minor glitch I’d encountered in my initial setup of the phone and urged me to reboot it. I did and suffered no more momentary dropouts.

TechCrunch: (MG Siegler)

This Verizon version of the iPhone 4 seems to have none of the same antenna issues. Try as I might, using the “death grip” and every other grip I can actually do, I can no longer reproduce the same attenuation problem that the previous iPhone 4 model had. I death grip the thing, and no bars drop. More importantly, calls don’t drop and data doesn’t stop. Again, Apple won’t comment, but problem, apparently, solved.

Engadget: (Joshua Topolsky)

So, does the phone exhibit more favorable behavior in regards to dropped / failed calls? The answer is yes – with a caveat. We had many, many perfectly connected and sustained calls while on the Verizon iPhone (many times during testing we actually had to switch from our AT&T device to the Verizon device just to complete the call). After a couple of days of use, the fear that normally sets in about five minutes into a connected call with an AT&T iPhone all but disappeared, and we found ourselves wanting to have longer talks and not worrying so much about the potential for dropped and interrupted calls.

But on to that caveat. While the phone did connect much more reliably and consistently, it wasn’t impervious to broken connections and sound quality issues. In areas where we had a weak signal, or when moving around, we experienced call interference (our callers noted this as well), and in two instances, we did drop a call when moving from one place to another (clearly an area with less Verizon juice).

So it seems like Antennagate is officially a thing of the past, some dropped calls were experienced, but it depends on your area. No surprise there. It’s just the same iPhone 4 on a different carrier, which means a great device on the network people were waiting for.

As noted by TiPB, Verizon has released a first version of its Contact Transfer app in the App Store. The free iPhone app, which only works with Verizon iPhones and won’t do anything on your AT&T device, can import contacts from your previous Verizon phone using the external Backup Assistant service.

This application is only for Verizon wireless users. Download the free application to transfer your contacts from your Backup Assistant device to your new device. All your contacts will be transferred to your new device with in minutes.

Backup Assistant is the service Verizon uses to let customers save their contacts in the cloud and easily restore them on any device. The iPhone version will behave just like you’d expect from a Verizon handsets, although I guess for Mac users it should be simpler to just sync their Address Book using iTunes. Or, if you’re a MobileMe subscriber, activate contact syncing over the air. Still, if you happen to have an old Verizon phone and you never backed up your contacts to the desktop, this app might help during the process.