I'd give this player 4 stars because I caught it as a deal of the day, but I want to be more subjective on the value proposition. At the current sale price (as of 6/13/18), it's an okay value and earns 3 stars, but I'd probably pass and wait. At it's regular price, I'd avoid it like the plague because you can spend a little more and get a more fully-featured player with WiFi and streaming capability. For most people, I wouldn't recommend this, but if you already have a streaming box or a smart TV, it might actually be worth it to you.
I picked up my LG UP875 4k Blu-Ray Player as a deal of the day about a month ago. I had been wanting to upgrade from a standard 2D-only Blu-Ray player (Samsung BD-J57, which is a decent Blu-Ray player) to something that does 4k Blu-Rays along with 3D for the few 3D titles I own. The UP875 fit the bill as I didn't need streaming apps on the player (smart TV, streaming player, and a PC are part of my home theater setup).
As a stand-alone player, I'm pretty impressed. Video quality is great on every format it supports, DVD upscaling looks good, and discs run smoothly. Compared to the Blu-Ray player this replaces (Samsung BD-J5700), movies load faster.It also does great with content stored on hard drives, flash drives, and even files burned to discs (single and dual-layer DVDs and Blu-Rays are compatible - and CDs too) as long as the content is DRM-free. The biggest limitation some will come across is file system compatibility on flash drives and hard drives - this can only read FAT32 and NTFS hard drives, so if you make backups of your movies for the kids and you run a Mac, you'll probably want to invest in a USB DVD burner.
Do you have an Android phone? The UP875 will also play back any media you have on your phone, as long as it doesn't have DRM protections on it. This is something I didn't get to play with, however.
As far as the unit's aesthetic qualities go, the smooth front is a very clean look, as opposed to the "busy" front side or competing players. An indicator glows red for standby or green for on. Also, minimalist front-panel buttons are a nice touch and don't detract from the styling of the unit.
So for what it lacks - anything to do with streaming. It doesn't do. No Netflix, no Vudu, no YouTube, no Hulu. It also doesn't support DLNA or file-level browsing on your network, or media servers like Plex. It only has a single HDMI output, so if you have an older AV receiver that doesn't support 4k HDR (or 4k video), then plan on either upgrading your receiver or only getting 5.1 audio from the player (via optical or your TV's HDMI ARC connection).
All told, this is a great disc player and a good option for playing media from external hard drives and flash drives. It's lack on network options is disappointing and unexpected at it's MSRP price and "sale" price (sale price as of 6/13/2018). As a deal of the day, I give it 4 stars. At it's sale price (and it's usually on sale), I give it 3 stars and only recommend it to those who already have a streaming box or smart TV. At full price, however, I can't recommend it and would tell you that you're better off spending another $50 to get a player with streaming functionality. If LG would fix this part of the equation - EVEN WITHOUT WIFI - I would feel better about recommending this player for most people looking for a 4k upgrade.