A 4th gen Glock will have curved serrations on the slide & bunch of raised dots all over the sides of the grip. Here's a pic of a 4th gen Glock 22:
Also, the 4th gen glocks have a removable backstrap so you can customize the size/feel of the grip to an extent.
That sure looks like it's the fish-gill generation that was pre-Gen4 and didn't get the following that it should have.
The Gen 4 has the new widened mag release and is reversible, interchangeable back straps, less aggressive front strap finger grooves, and is available in the RTF2 while they last. The RTF2 will become a LEO only package eventually.
This is what a Gen 4 should look like, note the wider and elongated mag release and the texture. Don't get me wrong, the fish-gill gen 3 was sweet.
http://www.ammoland.com/2010/01/24/glock-22-gen4-and-glock-17-gen4-pistols/
I still wish Glock would wise-up and install the extended slide stop on all of their pistols. Of course, after owning a Glock 34 I'd also like to see that trigger package in all of their pistols....sah-weet!
Back to the Lasermax issue. I've only had experience with the early generations of the Lasermax products. I didn't like that I had to disassemble the pistol to turn on the laser, so I stayed away from it. If they've changed/corrected that issue I'd again look at their products. I've used the Crimson Trace units myself and like them, but I'm not keen on how bulky it makes a Glock look. Why oh why can't Lasermax, CTC, and Glock get together and build a pistol around an internally mounted externally activated laser?
Well, Lasermax changed A LOT from the gen1!
http://www.lasermax.com/installation_guides/pdfs/Mini_Glock_Manual_-NP.pdf
Note, the Lasermax will not fit the Gen 4 Glocks.