Lots of Glockers out there consider the Gen 2 Glocks to be the best models they've made and nowadays these Gen2 guns have been flooding the surplus market as departments upgrade their guns to the newer Gen4 models. The good news for the public is that while most of these guns were carried a lot and show some wear, many were shot very little over their lifetime and have plenty of life left in them.
-Reliable. The gun has had 0 malfunctions
-Accurate (more accurate than I am)
-Durable. The Gen 2 guns are where Glock built their reputation for durability.
-Easy to maintain
-TONS of aftermarket support
-Accepts 15, and 22 round factory magazines
-Glock has great CS
-Cheap replacement parts, should you ever need them
-Low Bore Axis resulting in a relatively soft shooting gun
-Requires very little cleaning/lubrication to run reliably
-Many people prefer the Gen2 grip without the finger grooves present on the Gen3/4 guns
-I'm not a fan of the Glock factory plastic sights
-When I first inspected the gun, I noticed the slide stop lever had almost no spring tension and replaced it. What I'm getting at there is that you'll certainly want to inspect the guns because some departments out there do very little armoror work (if any at all) on their guns.
-Gen 2 40S&W Glocks are famous for being vulnerable to "ka-booms" due to a partially unsupported chamber. I personally believe the majority of this these incidents occur due to reloaded ammo but nonetheless it's worth noting.
Here's a video with some shooting from the 12m line, break down the gun, compare the chamber support to a Gen4 Glock, and discuss the pros and cons of the gun: