Don't be fooled by the Mac Mini's internal hardware. It may not have been updated in a few years but it's still capable of outputting to a 4K monitor and even editing 4K video with ease. I purchased a 12.9" iPad Pro last year and found myself using it more and more instead of my notebook. I would turn to my MacBook Pro only when I wanted to do very specific things, like encode a video in Handbrake. So I sold it off and decided a Mac Mini would fit that need just fine. At the time, it pretty much had the same internal hardware as the $1200 iMac but I didn't need the monitor (not when I have two 1080p monitors sitting at my desk).
Overall, I've been pleased with this little machine. The dual-core Core i5 is still a solid CPU and only marginally behind the current generation in terms of performance (it's about 15% the new Kaby Lake chips when it comes to benchmarks, big deal), 8GB of RAM is more than enough to accomplish basic and even more advanced tasks in macOS, and I forgot what it was like having access to so much built-in storage after migrating from a 128GB MacBook Pro. Apple also included Bluetooth 4.0, 802.11ac, there are four USB 3.0 ports, two Thunderbolt 2 ports, analog audio in, analog/digital audio out, an SDXC card reader, and HDMI output. There's also a front-facing IR port but I think it only works with the older, silver remote and not the new touchpad remote.
The one thing that still shocked me was how small this desktop is. It's about the same size as older set-top-box streaming units but packs a lot more power in an elegant anodized aluminum enclosure. Overall, I have found three negatives with the current Mac Mini. The positives were more than enough to outweigh anything I have against the Mac Mini but I will list them anyways.
First, it is a pain to upgrade the internal hardware of the Mac Mini and the only thing you can change out is the internal storage. The RAM is now soldered directly onto the logic board and is no longer user-replaceable. It takes quite a bit of time and effort to get the black rubber cover off. After you've spent 15 minutes doing this, you'll be greeted with an aluminum sheet held on by hex screws. It's only after removing those when you'll start to see the internal hardware but even then, it takes a couple of minutes to finally get to the hard drive. This really shouldn't shock anyone in this day and age as Apple has long been making non-upgradable PCs. The Mac Mini used to be the last holdout after the iMac but that's changed now. Make sure you get whatever features you want upfront as you won't be able to add anything else except external components later down the line.
Second, I really wish this would of come with a Fusion Drive as standard even if it was a 1TB Fusion Drive with only 64GB of SSD (instead of the 128GB standard). Going from a MacBook Pro with SSD to a Mac Mini with a hard drive has taken some getting used to. Programs take a good 4-5 seconds longer to open, it takes longer to load things, and rebooting the system takes a while. Once programs and things are loaded, the Mac Mini handles them well just like any other Mac with SSD. It' the initial opening and loading that adds time.
Lastly, I definitely wouldn't pay $699 for this. For that price, the internal hardware is too old and you should be getting an SSD (or at least a Fusion Drive) standard. I purchased my Mac Mini when it was on sale for $599 and I had another coupon that dropped it down to $499. For that price, it's a pretty solid desktop for those that prefer macOS to Windows. At $699, it's an expensive system that's not worth it. You would be better off saving up and getting a new iMac instead for $300 more.
That being said, I'm fine with the internal hardware at the price that I paid. It encodes 1080p, h.264 movies (with stereo AAC and 5.1 Dolby Digital sound) in less time than it took my 2015 MacBook Pro (and even Surface Pro 4), takes up very little desk space, is still a sharp looking machine, and it pretty quiet (I've never really heard the hard drive or fans kick on). It has served it's purpose and is exactly what I wanted out of a desktop.
I highly recommend this to anyone who wants to dip their toes into macOS or someone who needs a newer desktop but already has a monitor, keyboard, mouse, etc. Just make sure you wait until the Mini is on sale, otherwise it's not worth the $700 price.