Saucony Guides are my absolute favorite running shoes, and the improvements Saucony makes in each iteration of the Guide consistently make them a better shoe.  I started out with the Guide 3's as a new runner, and since I didn't run very heavy mileage back then, I managed to keep the 3's in constant use until the 5's came out.  The 5's were actually quite a large overhaul - the heel-toe drop changed from 11+ mm in the older models to aslight flatter 8mm starting with the Guide 5's.  This may not be a big deal to you if you wear your shoes for activities other than running, I don't know, but for runners a drop that changes actually changes the shoe quite a bit.  I was hesitant in my first few runs, because I could feel the heel-toe transition was flatter and my shins were tentatively twanging a warning to me after my first 10+ mile run.  However that was as far as the issue went, and my body quickly accustomed itself to the new angle and I've never been able to go back to the larger drop shoes again.

At this point I'm running 40-50 miles per week, and Guides are still my favorite shoes. I've tried Brooks and Nike Lunar Glides, but the Saucony Guide is the only shoe that feels like it is absolutely molded to the shape of my foot.  The upper is breathable mesh. The tread and cushioning are durable (I'm able to take them 450+ miles) and the shoe itself is light and springy.  The toe box is roomy but not weirdly so.  I actually found that the slight bit of elastic in the laces is a huge plus, too - it allows the top of my foot to move without getting bound by tight laces, but keeps the pressure firm enough not to slip.  I know the Guide 6 is even lighter, but quite frankly I'm so happy to be able to pay around fifty bucks for the 5's and stock up a few pair in rotation, I don't mind not having the latest rendition.