"It is probably the perfect optic for the AR, isn't it." -Shawn.
I stumbled across an old email from 2013 where I told a friend that I thought the T-1 was the king of reflex optics. Despite there being the newer T-2 and similar optics like the Trijicon MRO, I still stick to my statement.
What makes the Aimpoint Micro T-1 great is very small size, light weight (3 oz with out mount) and long battery life of up to 5 years. That makes a combination that is hard to beat.
There isn't much not to like about the T-1. Now if you wanted to start a list of complaints the first would be cost. After that is that the stock mount is low profile so you would need to either add a riser or use an aftermarket mount if you are attaching it to an AR15. I prefer the Larue QD mounts for the T-1 but that does add to the price of the optic.
When people talk about the massive battery life of modern optics like the Aimpoints, they are referencing the possible battery life at about three quarters maximum brightness (a normal operating brightness). When the T-1 is set to maximum brightness, this battery life is shortened to about 10 months. But to put it in perspective, the Trijicon MRO also has a battery life of 5 years on setting 5 of 8, but only 25 days on the brightest setting. Many older optics and cheap optics will only run for a few days.
The T-1 is available in 2 and 4 MOA models.
I have a hard time getting the reticle to show up well when I snap photos of them.
Here is a picture of a 2 MOA T-1 with the brightness on max so the dot would show up in the picture. This one has an IO/Tango Down cover installed, and a KAC battery cover.
This is a 4 MOA T-1 on a Larue LT660 mount. The dots show up clearly and bright in person, I don't know how to get them to show up in pictures well.
Adjustments are 1/2 MOA. Adjustments require a tool, which is provided as the cap for each adjustment. Be careful as it would be easy to lose the adjustment caps.
Flipping the cap upside down allows you to use it as the adjustment tool. It shows you which direction you need to turn for the adjustment.
Now I would say that the only real downside to the T-1 is cost. But if you run it co-witnessed with fixed iron sights, the small window makes it a little harder to use. You might want to consider a larger optic if you are running it with fixed iron sights.
It is normally recommended to go with the 2 MOA models. You can turn up the brightness if you want a larger visible dot, and it is suppose to look better if you are using a magnifier. I have a mix of 2 MOA and older 4 MOA models, and much to my surprise when I was using them size by with with a magnifier the 4 MOA dot was crisper under magnification.
For a long time I said I never saw an Aimpoint fail, but more recently I have. Both cases were user error. The first was an used T-1 I purchased where the previous owner cross threaded on an aftermarket KAC battery cap. When they attempted to remove it they put a wrench on the stuck cap and turned the brightness adjuster past its stops. I sent the optic back to Aimpoint and while it took a while, they repaired it and sent it back at no cost. The second case was my fault, and a really simply error. I have a KAC battery cover, and this cover has a space so you can put a second spare battery in it. I didn't have the second battery under this cap, so then under recoil the battery would pop out of place and my sight shut down. Installing a second battery (as per the aftermarket cap requires) solved this issue.
I love how small and light the T-1 is. When used you can sort of see around it when you keep both eyes open and it takes up much less space in the view than most other reflex sights. I've bought all of mine used, as they are hard to screw up and and you can save a good bit of money getting it used. The Micro T-1 is easy to use and I highly recommend it.