EDIT 26/8/2016: I have been using the specific backpack on a daily basis and it has proven a reliable companion for me as a commuter. It has been used for my daily commute to work carrying my 10,1-inch tablet and food container, during weekends for carrying stuff for my son’s basketball courses (towels, water bottles etc.), even during short trips for carrying my gadgets (tablet with keyboard, chargers, cables and hard disks) and other stuff like sunglasses, wallet etc. I would not expect that it would last that long and I am happy for that 🙂
EDIT 21/12/2015: I have tried squeezing in my 15,6-inch Acer E15 ES1-512 but it wouldn’t fit in the padded compartment; it fit in the main compartment but since I planned to use this for larger items and have the laptop in its space, I had to change plans. A deal breaker for the specific backpack.
During one my visits to Plaisio for having my tablet serviced, I got attracted to their laptop bags/backpacks; I am a sucker for such bags anyway and since my previous one (a lovely DeviantArt Pro Digital Artist Backpack) was a little worn out (and has to be repaired), I was looking for a temporary replacement.
After unsuccessfully trying a messenger bag for the first time in my life (I tend to carry a lot of stuff daily and a messenger bag was not exactly comfortable), I ended up with another Plaisio-branded Sentio Sporty Backpack for a 15,6-inch laptop.
The bag is very light (and I mean light!), has a number of individual external compartments/pockets with zippers. I am not exactly sure if it is waterproof and it doesn’t seem very durable (the material is thin and soft, like a thin windproof jacket) but still it does the work. The main compartment fits a 15,6′ laptop the but for the time being I usually carry my Wintab and a book in this padded pocket and my food container in the rest of the space. There is also a top, smaller one for wallet, ID and chargers, a smaller external one for keys and my external hard disk as well as a bottom one for small notebooks and USB flash drives.
None of these includes an internal pocket with zipper for storing safely e.g. a smartphone or the wallet, neither a really useful ring for the keys (so I keep looking for them each time). Pen holders are short and pens keep falling off them and the rest of the internal dividers are loose and had to keep small stuff. The bag is really spacious though (35 liters, according to the manufacturer) but I wouldn’t put too much weight in it as it doesn’t seem that durable.
The straps are really comfortable but the handle is attached to them (instead directly to the bag; it is obvious that the bag material could not handle the bag’s weight from the handle) and this makes handling it a little awkward…
It is a compromise but still it looks ok for casual use, commuting to work before it breaks (at least until I have my Deviantart backpack fixed). I could buy a branded one for the 25 euros I paid for it (e.g. a couple of Belkin & Case Logic models at a nearby store and probably more models after a market research) but I liked the more “casual/sport” looks of the specific one 🙂