It's nice to be the BES Administrator sometimes - especially when that means getting a new BlackBerry to "test". I just acquired the Blackberry 7100G yesterday. I upgraded from the BlackBerry 7280.
Other than the aesthetic overhaul (the 7100G is a nice-looking SmartPhone), the major differences between the two are: screen type, GUI, bluetooth, polyphonic support, and keyboard layout. There are pros and cons with each, so let's go through what I've seen so far.
While both screens support "over 65,000 colors" (65,536 = 64k), the new LCD screen on the 7100G is much more clear than the "color reflective display technology" used on the 7280. The 7100G also has a better/brighter backlight than the 7280. While the LCD screen is far superior, it can have drawbacks (partly due to having the glossy plastic cover). The main drawback is glare in the sun or other bright lights. If I can say one good thing about the 7280 it was that the screen was very readable in the sun. Also, the 7100G's screen is laid out in portrait instead of landscape like its predecessors.
The 7100G also has a text-based, menu-driven GUI as opposed to the icon menus on the 7280. There is software available for those who would prefer the icons. I am indifferent to either GUI, so this is not a problem for me.
The 7100G is the second-generation Bluetooth device from BlackBerry (the first being the 7290). While this is a wonderful enhancement to allow you to use a wireless headset, the drawback is that its only use is for a headset. With polyphonic support it would have been nice to see software to allow you to send midis/ADPCM files via Bluetooth.
This is one of the best features of the 7100G - actually having decent ringtones! The ringtones on the 7280 sounded harsh and Atari-like. While polyphonic midis are great, there is the ability to add ADPCM (MP3-like) tones to the phone as well.
While the 7100G still has a QWERTY keyboard, it is now using BlackBerry's Suretype technology. It is somewhat like the T9 predictive text used by other mobile phones. This is the first qualm that people have when they see the 7100G - "That keypad is strange, I don't like it." Well, after using it some, it is not really difficult to work with. I actually rather like it - having two letters on most of the keys is great because it allows the phone to be slimmer and makes thumb-typing drastically easier than on previous BlackBerries. Speaking of that, now that the phone is slimmer it doesn't feel like you're holding a calculator to your head when talking on it.
Other than that, there are some other nice features. Most of the minor enhancements have revolved around making the BlackBerry a better phone. They have actually added "place call" and "hangup" buttons. This is great because on the previous phones you would have to click the scroll wheel to answer (sometimes causing you to scroll down to "Ignore" before clicking - thus dropping the call!). There is also a speakerphone option that can come in handy. One strange option is the standby mode. After the backlight shuts down the screen just turns off. This is good for the battery, but it's just a strange quirk with the device.
Overall, I really like what BlackBerry has done with the 7100G. I have even noticed better phone reception when driving along a stretch of road on which my 7280 would lose the signal completely.