I bought this guitar approximately 1 year ago, before writing a review I wanted firstly to get know the instrument. So this is what I can say about this S521:
firs of all, the guitar is really light waited, bit neck heavy, but that does not make a big difference to me, haha. the neck is thin which makes it easier to play (in my opinion), in comparison to other guitars I tried before buying this one. The total feel of the guitar in the arms are really pleasant, it is like holding a baby, Haha!
The actual sound of the guitar unplugged is pretty decent, and when plugged even better, then I expected. The tuning holds really well, even in low tuning (I mostly play in D-standard or Drop-C).
The only issues I manage to find are that the backside of the guitar body is quite soft and because of that it received some use marks from clothing and that the neck picks up (or how it is called, the one near the neck) get loose overtime when played and gives buzzing sound, but also it is quite easy to tighten it up so that's ain't a problem (i do it even with a pic).
I mainly play heavier music on this instrument, such as Black metal, Metal in general, Stoner rock, etc., and do not have any complaints about usability.
Furthermore, when other guitarists checked this guitar (the ones who play guitars for quite a long time), they were pleasantly surprised, as they expressed themselves. also, some of them hated thin neck or lightweight but is it personal preference.
Overall, this guitar is a real bargain in accordance with the price and quality ratio! Realy good as a first guitar, easy playability out of the box, strived me to learn how to play the guitar quite quickly (at least basics, writing riffs, low-level solos, recording). So, personally, I really recommend to spare some more money and buy this guitar.
And for those still doubting about learning guitar or another instrument: If I did it, You can do it Too!