What I like most about this device is it puts Ableton's Session view launch capabilities into a physical, easily accessible midi controller.  I have not used any of the Akai APC units, but this thing seems to be the perfect answer for anyone who uses Ableton in a live situation.  It makes things super easy by allowing each pad to light up yellow (to show you there is a clip that there that is not being played) Green (shows you a clip that is currently being played) Red (clip is being played and is in overdub/record mode) and of course no light to tell you there is no clip in that region.  Another great and essential option on this device is to control different areas of the session view trigger grid.  On the screen in ableton there is a green box surrounding the area that the Launchpad is currently displaying.  By using the arrows on the top, you can move this box to display any area in the session trigger screen.  This is great (and fun to watch), as you can launch any clip on your screen, and, if you are pretty familiar with your set, you can move around comfortably without looking a the computer screen.  On top of that, you can hold down the session button and the lauchpad will allow you to "jump" to different areas on your screen.  Say you are launching clips in your set at the top portion of the screen and you want to launch a clip all the way at the bottom many rows down.  Hold down that session button and select the grid (in this mode, each button represents a whole grids worth of clips) and select what "grid" you want to jump to, in this case, the bottom one.  The great thing about this option is that the Launchpad will only show you areas that have clips in them.  If thats confusing, check out videos on Youtube and it will make sense.  There are many more great features about this device, but I could spend all day talking about them. 
What I don't like most about this unit is that for some reason (and I can't understand why) when you a pad down, it will "double-click."  What I mean is that you push it down and it will "click" once, then you push a little harder and it will "click" again.  Every trigger reacts on the first click, so the second click is completely unnecessary.  In reality, its not a big deal, it just feels weird and is a little annoying.  As for my opinion on the price, I paid $180 for a brand new one shipped to my door.  Overall, its functions make it worth every penny.  But, when I first got it, it was smaller than I imagined (the person in the photo must have very small hands) and its made of very light weight plastic.  For around $200 bucks, they could have used some cheap metal or something, that would have made this thing feel like a real professional piece of gear instead of a cheap toy.  No sound quality from this device, only midi operation.  I have a couple of M-audio boards that I was using to trigger clips in ableton, but they don't even compare to this device, mainly because of the "light up" buttons.  Yes, I do wish it was made of stronger/heavier material, but I would definitely make the same choice again.