Synology made a great move with the DS414slim since they managed to pack the power of their DSM OS, two Ethernet ports, and USB 3.0 support into a very small, nicely designed unit. The NAS looks great, and its small footprint greatly increases its usability. In short, it will be the ideal unit for an overcrowd office environment, or for users who want something elegant, but lack a lot of space. It can also easily be placed anywhere in your living room without being visually intrusive, and take into account its silent operation and you truly have a worthy bundle. Its small dimensions didn't allow for a stronger CPU since it would need a larger heatsink, which would have affected the cooling fan's size, but stay away from RAID 5/6 configurations and you won't notice a considerable drop in network transfer speeds. Surely, its CPU isn't a speed demon, but it will definitely cover the needs of the average user. The most significant limitation is the limited storage capacity 2.5" HDDs have on offer compared to their 3.5" counterparts, but accomplishing such small dimensions without making a few sacrifices simple isn't possible. The DS414slim's most important features, other than its small footprint, include the USB 3.0 port in the front, which increases its usability, its two Ethernet ports, a great feature in a NAS belonging to this category, its semi-passive fan mode you can enable in the OS, the two bundled licenses for camera channels in Surveillance Station, and all the features the DSM provides. I think you would be hard-pressed to find an alternative with as many features in such a compact unit.
As you will probably have figured by now, I liked the DS414slim very much. It hides much more than meets the eye and will earn the respect of all users looking for such a small NAS unit. It may not offer ground-breaking performance, but its performance will suffice for normal use at home. If there were a performance-to-size ratio chart, this NAS would have been on top. If you need something elegant, really nice, small, and fully featured, the DS414slim is the perfect candidate. Its price surely is on the high side, but you shouldn't forget that the smaller something is in the IT world, the more money it will costs, and this NAS isn't an exception to that rule. Synology put a lot of effort into producing and releasing such a product, and they should be proud of the outcome. I expect them to release an upgraded version of this NAS in the future, with a stronger CPU, more RAM, and an HDMI port to thrill even more users who want or need the computational power of a richly featured NAS with such a small footprint into making the purchase.