It has a 3.5" QVGA, which is what my X30 high has, compared to the X51v's 3.7" VGA screen. Honestly, the QVGA screen isn't that bad at all, though photos and movies do look a lot sharper on a VGA screen. If you want a good analogy, go from a resolution of 1024x768 to 800x600. Ignore the size difference, and just look at the overall quality...that's what it's like going from VGA to QVGA.
If I had a choice between the two, I'd take the VGA screen over the fingerprint reader. Why? The fingerprint reader won't work right if your fingers are dirty or oily, and can be fooled by the proper gummy treat. HP pulled the finger print reader from their PDAs for a while due to the complaints of low accuracy. It's much better now, but standard consumer fingerprint technology is still not good enough for me to rely on. If you want an easier login than typing in a password, try a picture password...tap a certain number of spots on a photo of your choice. Just my preference.
Hope this helps,
John