I own two Gen2 Glocks: models 17 purchased in 1997 and 20 purchased in 1991. Both continue to operate flawlessly. Several years ago, Glock advised me the non LCI extractor for my 17 Gen2 was no longer made and replacement with a new LCI unit will necessitate the replacement of the extractor plunger and bearing unit. This is not a big deal to me, but does change the "drop in" parts replacement idea somewhat. Before supplies dried up, I just bought a couple of non LCI extractors at the time of the advisement as insurance. Spare parts are never a bad idea.
Depending on exact model number and date of manufacture, some Gen2 guns need updated internals. I had one that did and Glock did that at no time or material costs. I did have to pay shipping to Glock in Smyrna, but then the upgrade was at my discretion. Just a cost of ownership to me. Glock paid for S&H back to me.
There is no reason to believe the Gen2 guns are any less durable than Gen3 or Gen4. Individual guns may have problems, all mechanical things do, but as a model the Gen2 guns are every bit as "strong" as any other Glock. Some even believe the earlier Glocks are stronger. I own multiples of Gen2 Gen3 and Gen4 and over the years no model has exhibited superior or inferior durability.
One bit of advice. Remove the slide and examine inside the frame. It always pays to "look under the hood" before buying.