I got mine last Friday with an already carved shell. Installed it that same day, and I've been playing games on it on and off through the weekend. The initial instalation was a bit of a pain, although that had more to do with me not having any kapton tape and improvising around that, and being clumsy with hardware in general.
Overall, I'm in love with it. GBA games look super crisp on it, and the colors pop out thanks to how bright the system is (by default, much more so than an AGS-101, to the point where I find it a bit uncomfortable to use it in total darkness). Games that were designed to compensate for the dark screen of the AGB-001, like Super Circuit or the SMW port, do not look that great, but most games look gorgeous. The 'extra' pixels are very noticeable: while the aspect ratio is correct, the display itself is slightly larger than that of a regular GBA, which also means you'll need a lens with a thinner bezel for your unit. All of this makes for a very clear and vibrant image at the cost of a lower PPI count. If I had to compare the screen to anything, it'd be to a phone running the games through a GBA emulator: much clearer than what the original hardware displays, but also more pixelated.
Now, I know many games had their sprites designed for screens with a grid, but its absence doesn't bother me too much. It's more noticeable while taking a look at isometric '3D' games like The Urbz or the Lord of the Rings games, but the more traditional pixel-art part of the catalog looks great. I didn't bother with the soldering needed to adjust the brightness of the display, since I didn't have the tools for it, but I can see how lowering the brightness a bit might help those who are bothered by this.
A big, big bonus for me is the lack of ghosting/higher refresh rate when compared to the AGS-101. When I play fast games like Metroid or F-Zero on my AGB-101, they definitely feel slower compared to how they play on other systems. I'm not sure if it's a refresh rate issue, but there is a noticeable difference. Those same games feel just right on this display, much closer to how they feel when playing them on a Micro or DS Lite.
One thing I haven't tested yet is the impact to battery the screen has when compared to other displays, but I'm not even that curious since it's good enough for me.
In short: as someone who loves the GBA and its games dearly but has always been bothered by the pros and cons of each model, I've finally found my preferred way of playing 99% of its games. I highly recommend it, especially for the price. I'd post pictures, but my phone's main camera is busted. Both of my modded GBAs look like this, for the curious: