Well the Pro's keyboard doesn't appear to slide.. that is a Droid2 (3 now). My coworker raves about her X after losing her 2 to a toilet bowl. It has been mostly about the extra bulk of the keyboard adds.
But now there is an X2 and a Droid 3, and the 3 sounds like it is about the same size as the X but a little heavier. Better specs, duo core processor (supposedly less power use, more powerful), larger screen (questionable display technology), thinner, much better keyboard than the 2 previous versions.
The Pro has a relatively tiny screen. I am not sure what the appeal of the Pro would be? They may be giving them away at this point.
The real choice seems to be if you want a physical keyboard or not. X2 for none, D3 for physical keyboard. Otherwise feedback I've gotten are they are similar.
edit: if you want a free hotspot, you can root either and add a wifi hotspot (or bluetooth), otherwise you can pay $30/mo or whatever verizon asks for it. Verizon has also switched to tiered data pricing so if you don't have the older unlimited/$30mo data plan, be careful with how much data you use (I use NetCounter to keep track and am never close to 1gig a month). Rooting the phone also lets you use Titanium Backup, which lets you suspend (freeze) bloatware apps verizon/motorola installs for your pleasure, yet bring them back if an OS update comes out.
I've been very happy with my Droid2 Global. Great phone, meets what I wanted,
amazon was selling them for $.01 with 6mo minimum use committment.
