The Thecus N4100 Pro is supposed to be a budget model. Hence the performance isn't on par with the more expensive units. While read performance is good, write performance suffers a lot. That being said the N4100 Pro does offer all the features more expensive units do and is therefore suitable in basically any situation that doesn't require huge file transfers to the device regularly. To put it in perspective, you can still easily stream HD video from it, it will just take a bit longer to put it on it in the first place.
Considering the fair price (most four bay NAS devices cost more) and the large amount of features I can't do anything but praise it, at least as the center of a home LAN.