Is it worth the money? That depends, and will be different for everyone ... For casual use or even some competition, a DI AR will still run fine. The SCAR is supposed to be very reliable, but I havent seen it outgun anything else in my collection (unless youre trying to pass the over the beach test, then it would beat a few).
It is slightly more accurate than my Colt Hbar, but that might just be because its a shorter barrel with a shorter sight plane and iron sights. Its slightly better than your average AR, but not as good as your extra fancy match grade. (of course this is just my anecdotal account, others might be better or worse)
It will probably not be replacing the M16 in the next few years, although it does stand a chance. I personally think that an upgraded M16/M4 will be selected. I dont think it will overcome the AR in the civilian world either, I can get parts for my AR's, not too many for the SCAR. Until its costs go down, it will continue to be a niche platform.
Is it better than a piston AR? depends on who makes it, HK's 416 is statistically about even with the SCAR on reliability, "better" is a subjective term. Better by accuracy, reliability, lighter by weight, compactness, performance at distance, ability to handle differing 5.56 loads, ability to change calibers... What kind of better are you looking for?
I dont know how many rounds it will take before a failure without a cleaning, with the amount I paid for it, I take care of it. I clean all of my weapons after each use, if im in a class or at the range, I'll clean during a break. In my old job, weapons maintenance took priority over sleeping and eating, old habits are die hard. I would expect that with its operating system, it would go longer than a DI AR (assuming it hasnt been lubed during its firing) about the same as some of the more reputable piston systems, and a bit less than an AK.
Most of the reports you get are going to be from civilian users, as I dont think too many rangers or guys from 10th group are going to publish end item user reports. The internet will be full of rumors and half truths, some for some against.
Its a lightweight piston system that takes stanag magazines and theoretically has the ability to swap calibers, SOCOM wanted this specific ability so they could minimize the training on the platform in an attempt to find a way to reduce their logistical load. Many of the advantages it offers is lost on civilian users.
It's expensive, with limited after market additions, and I wouldnt buttstroke anyone with it. But its got a reliable operating system and has some interesting features.
I bought it because I like collecting new and different operating systems, and it intrigued me, but I had the money to spare and could afford it. If its going to strain your budget, dont bother, get an AR and spend the extra money on ammo and be happy with it. If you can afford it,along with the optic of your choice with it(I hate seeing scars with $30 knockoff red dots on top of them) and a good shooting school to help you learn how to use it, than by all means go for it.