The main idea on a side zip boot is to have the quick on / off ability, yet this is certainly easier said than done. I've tried ones where the zipper falls down with normal use, and I've had ones where there is no way to get them on without dicking with the laces making them easy off only. It does take a little trial and error to dial in a reasonable tightness while still able to zip them on, but I'm very happy at the balance I was able to find. I just tuck the laces in off to a side and totally don't have to mess with laces taking the boots on or off now. I'd say the Side Zip Duty Boot is even quicker to secure on than the Blauer Boa lacing system, however it doesn't have the fine tuning after. Some folks worry about zipper durability in extreme situations such as troops deployed for a year at a time so the main target customer of the Side Zip Duty Boot will be for domestic tactical jobs such as law enforcement. The zippers should last for the life of the boot, yet won't be a big deal to address any starting issues. The same concept applies to the choice to put zippers on pant flys or not, typically these days the convenience is worth the small risk.
Starting features to make the zipper functionality actually work right includes using a premium YKK zipper and self locking slider. The zipper won't want to move unless the tab is pulled and is further secured with a hook and loop cover strap. Although First Tactical makes non waterproof version for a bit less, this particular version is waterproof which is a nice plus. Using a mix of 45% full grain leather, 20% PU covered leather, 35% synthetic and waterproof membrane lined construction the result is a boot that keeps your feets nice and dry. One needs to be reasonable and they aren't going to protect you from water slogging through a knee high river, but they have held up great wrecking through rain, puddles, and of course wet terrain.
One of the design goals of the Side Zip Duty Boot was to have the support of a tactical boot while having the running shoe type comfort and I think First Tactical achieves that quite well. The break in period for me was quite minimal where my only complaint was they were a little stiff leaning forward, say if you are trying to do a calf stretch, otherwise very comfy with a nicely padded interior. After logging in some miles in the boots I was able to get the flexibility vs support balance I was looking for. I don't know much about tread design, but the tread appears to be a good mix of chunky and minimal for varied terrain. You will get traction and low noise in urban areas while still having enough tread depth and flow to deal with some muddy areas. I'd say the only possible small con I can think of is there is no obvious fastrope notch on the sole that seems to be incorporated to many boot designs these days. That said, if you don't like boots with exaggerated arches, you will probably like the First Tactical Side Zip Duty Boot series and the sharp angle arch zone can help some with fence climbing work.
For other nice design touches the heel pull is made of webbing with interior elastic to keep it nice and flat. There are also tongue lace pockets and stash pockets on the upper sides of the boot (approx 3.5" deep). I totally missed these until seeing them noted on the store product page. The tongue pocket actually has a lower opening which I haven't seen before, but does work out nice to push the lace slack up out of the way. The extra sewing on the side stash pockets does a great job concealing the fact they are any sort of pocket.
To complete the combo I was able to check out some of First Tactical's Performance Socks as well. If looking for a thin and snug fit, these are the socks for you. They can take a little more effort to put on since snug, but good thin and snug socks can help a lot with blister issues from inner boot movement. Made of 25% Thermolite® Polyester, 25% cotton, 25% polyester, 20% Nylon, 5% Elastane you get a good balance of light / comfort / protection with moisture wicking properties.
I came into checking out the 8inch Waterproof Side Zip Duty Boot with pretty low expectations so it was nice to be pleasantly surprised to find them to be the zipper boot I've always been looking for rather than just reinforcing disappointment. Not only are zipper boots convenient, but can save critical time for tactical applications. The zipper isn't the only important part of the boot however and the Side Zip Duty Boot does a great job being a full featured comfortable boot while still offering great protection. For those who are around folks that seem to commonly drop the breaching tools in the wrong place they even have a safety toe version. Only the black color is currently available, but there is a 6inch boot version offered for further variant options.