Naim is almost the perfect antithesis to the 'absolute sound' ethos. If you are used to a system that is directed toward delivering timbral, tonal and spatial accuracy, a system that does none of that but concentrates on temporal precision can be too different to parse in a single bite.
The reverse often holds for Naim owners. They find other systems musically bereft, even if they appreciate the tonal and spatial accuracy.
I used to own a full-blown Naim system. For a season, when I went back to study, I worked part-time for a Naim dealer. So my experience is as someone who's owned it and heard a lot of systems comprised of Olive, Black and 500-series components (often mixed with non-Naim components) .
My take is not too dissimilar from Alan's. I think Naim has always had a strong suit that it's played convincingly well. My experience is that people who appreciate the house sound find more of the same is available further up the price-ladder, though Naim's penchant for offering external power-supply upgrades, while worthwhile, makes the process difficult in choosing between a component upgrade versus a power-supply one. In those cases, it's easy to unbalance the system and find that the costly upgrade needs correction with another costly upgrade in order to not sacrifice the whole for the sake of a small, but noticeable improvement (the same is possibly true of most systems).
My main criticism of Naim is twofold:
1) Like many companies, Naim 2013 is no longer the Naim of the founder. This may be good or bad, depending on your disposition. When I was selling it, Naim began to venture away from its core disciplines of producing CD players and amplification, and ventured into HT, multi-room, in-car audio (for Bentley) and servers. It began to suffer from a case of too many irons in the fire, with a resultant drop in quality control and a lateral detour into products offering greater digital connectivity but a frustrating and buggy UI and sound quality easily bettered by components further down the hierarchy.
I should note that I have no idea of whether my criticisms are still valid under the umbrella of the holding company Naim is controlled by with Focal Audio. I certainly appreciate the vicissitudes of the industry and how difficult it is to keep several generations of loyal owners happy while increasing profitability and maintaining some semblance of R&D integrity when many companies are in a race to the bottom. No-one wins when a company goes bankrupt and service and product support evaporates, so I can only hope Naim have secured a future in which it can continue to provide the highest level of support to its customers and provide products built with the highest integrity - that was certainly true when I owned my system.
2) Naim does have a house sound. PRaT is the most ludicrous and nonsensical acronym, and yet, "temporal precision" as Alan describes it is indeed one of the things a Naim system will exhibit best. The reason I sold my system and moved away from Naim is that ultimately, while their house sound is robust and does many things well, Naim systems tend to be harmonically bleached, emphasize momentum at the expense of flow, major on macro-dynamics at the expense of micro-dynamics (their speakers in particular), and fall short in the areas of texture, touch and subtlety. Music tended to suffer a degree of homogenization that while not unpleasant, nevertheless became too obvious for me to ignore. Spending more never resolved those aforementioned criticisms - you simply got more of what you already had. I mean, I love steak, but if I'm paying more I'd like to think my palette might be treated to something more refined and varied than just more steak. Music playback is an incredibly complex phenomena and, for me at least, can't be reduced down to some comfortable and well-worn acronyms not matter how fundamental an issue like time may be. (Of course, devoted followers of the Naim "cult" do to tend to be vociferously obnoxious in their defence of their beliefs and, if I'm honest, that did prove somewhat tiring to be around. Personally, I think Julian Vereker's greatest achievement was not that he created the world's best audio systems, but that he created a myopic adherent of people who thought that he did.)
It should be added that I've moved toward vinyl, tubes and horns, so you can see where my values lie now, and that obviously, it's no longer an apples-to-apples comparison.
But none of the above would dissuade me from encouraging someone I cared about to invest in a Naim system. The system-building approach and set-and-forget nature of their ethos suits many people who would describe themselves as music lovers first, and really don't want to think about whether biwiring with Kimber would be better than a single run of Tara Labs, etc.