Since its introduction to the PRS line-up in 2018 Silver Sky, John Mayer's signature model has triggered extreme emotions in the guitar community. It was pretty visible right off the bat that players became quite polarized about it: those who appreciated John Mayer and Paul Reed Smith's take on this classic style of guitar and those who generally acclaimed it as a "copy" and a "ripoff".
As far as the motivation behind creating PRS's version of the Stratocaster-style guitar, John mentions the inability to cooperate with Fender in creating a particularly spec'ed guitar he would find playful. On the PRS website we can read:

“It’s been a dream of mine for years to design a guitar that includes some of my favorite vintage specifications but with a modern spirit and aesthetic. After two years of study and refinement, the Silver Sky is my vision of what a reboot of the electric guitar should look and feel like.” – John Mayer

So, Silver Sky has strong Stratocaster roots, sharing the same scale length, three single-coil pickup setup, a 6-point tremolo bridge, the same input jack placement and a very similar body shape. It also tends to nod to more vintage-oriented guitar aficionados by featuring a 7.25" radius, which many modern players would find non-optimal performance-wise (a standard today would be 9.5" or even compound radius, even for Fender fingerboards). Upon a closer look, however, some features set it apart from Fender's classic Strat.

The headstock

One could say that this is the point where the guitar community has the most extreme opinions. PRS had to use their signature headstock shape, not only for legal (or lawsuit) reasons. Paul Reed Smith's iconic headstock design has more to it than purely aesthetic purposes - a more symmetrical shape with a 3+3 tuning keys setup allows strings to be perfectly parallel to each other and reduces the angle at which strings bend after the nut. This is specifically one of the reasons why PRS guitars stay in tune so well. Also, Silver Sky’s headstock is a mirror image of the classic PRS shape, making it the only model to feature that design.
Last but not least - top-locking tuners are a great addition to the guitar tuning stability, while still not a standard in classic Stratocasters where vintage tuners are preferred.

The electronics

Quite often we hear that no guitar sounds like a Fender Stratocaster. And we find it true - whatever magic Fender puts inside their guitars or the wood source they are using, nothing really sounds “exactly like it”.
When you pick up and plug in PRS Silver Sky you realize quickly that the creators didn’t want it to sound “exactly like it”. The first series in 2018 featured lower-output, midrange-focused single coils closer to the sound of John Mayer’s “Slow Dancing in a Burning Room”, yet with a PRS flavor. During the period of 2019/2020, the model underwent a series of updates (nitro finish, high-narrow frets, slight neck shape change) which included making the pickups a bit higher in output. It makes the sound super articulate and dynamic, rich in upper midrange overtones. It sounds substantially different from its counterpart and has a lot of air and boutique quality associated with PRS creations.

The craftsmanship

It starts with wood, and many people out there say that in the case of a stratocaster-style guitar - the lighter the better. Whether it’s true or not - the guitar is lightweight, and the grain of neck wood is straight with no knots. The fingerboard has an intense deep shade of brown and it is thick (think Fender slab board). The whole construction resonates from the tip of the headstock to the end of the body as a great guitar should.
Core PRS models are beautiful. Sometimes you might feel that they belong more to the art gallery or some well-lit store display rather than a stage, but they do feel right at home when played. Silver Sky is more modest in terms of colors (however there are limited runs such as Lunar Ice with stellar finish), so far no wood tops have been made available. In this matter, Silver Sky stays true to the vintage spirit with plain color options. They also don’t offer any kind of relic jobs just as in any other models of the PRS lineup - high gloss polyurethane (before 2019) or nitro lacquer. Everything in this guitar is shiny and flawless. The fret job meets the level of perfection of the paint job, frets are inserted clean, and edges are rounded and mirror-shiny. The hardware feels of high quality, plastic parts are nice to touch.

So are we talking a Custom Shop quality?

Fender Custom Shop has been associated with high-quality craftsmanship, more carefully selected woods, hand-wound pickups, etc. Also, final quality checks play an important role in how highly valued current CS guitars are. It is not uncommon for players to compare different variations of Stratocasters to “Custom Shop quality”.

Let me add a short disclaimer here: there is no such thing as “Fender Custom Shop quality”. Custom shop runs are different from standard models in their, well... Customizations. If you order a new Custom Shop Fender you’ll be able to pick some or all of the features on your own (or purchase a limited run made for your favorite guitar store, like in the case of Wildwood Guitars runs) and this makes a real value for a buyer. Sometimes people select fancy wood tops, they want superlight woods, special uncommon neck profiles, etc. This is what you pay for. Moreover, if you particularly love one master builder style, you can ask for a guitar made entirely by them, start to finish (some like Paul Waller do amazing relic jobs). And this comes at an additional cost. Custom Shop means a more careful selection of materials, personal customizations, and other bells and whistles.
In general Custom Shop Stratocasters produced currently are top-quality guitars with great woods, pickups, mesmerizing relic jobs, feel, and tone. The vast majority of them tend to steer towards vintage style. Does PRS Silver Sky meet these quality standards?

In my opinion, it does. Combining vintage features and sounds with flawless craftsmanship and more modern touches - it can rival the Fender Custom Shop guitars. But that doesn’t mean it will be better. Each guitar and each player are different and the quality of a guitar doesn’t exactly determine your feeling towards it. For those who like modern reinterpretations of classic models by boutique brands - PRS Silver Sky will be an interesting choice for sure.