I needed a case to fit my live PA techno setup into consisting of Octatrack MK2, Jomox MBase 11, Launch Control XL, Erica DB-01 Bassline, Elektron Analog Heat MK2, and some other peripherals. I wanted to have my setup ready to go at a moment's notice so all I'd have to do is put on the lid at the studio, carry the case to the car, show up to the gig, open the case, plug in 1 power cord and 1 stereo cable for the venue mixer, turn on, and go. As opposed to setting up for an hour or more at the venue with spaghetti cabling and troubleshooting. In terms of convenience and the amount of time saved, the case pays for itself in spades.
I am grateful that Thomann was able to ship it to me in the US for less than it would've cost to get a case here. By the way, no one makes cases commercially that are the size of the Large Thon in the US that I've found.
The build quality is everything I expect out of a hard case. I don't think it would be safe as checked baggage on an airline, but for gigging use from the studio to the car to venues it is more than enough. When it shipped to me, it did suffer a few dents on the corner pieces, but that's not a big deal and also that's what the case is for anyways. To protect gear not look pretty. Even though it fits that bill too.
I use 3M industrial grade velcro to hold my machines down. Thon did supply velcro strips that actually secure machines well. For lighter boxes I used the included velcro, and for the heavier or more expensive ones I used the 3M. The 3M however, I will caution that it can pull up the felt attached to the wooden panel in the case. The times it did happen I was able to press the felt back down to secure it again. This is not an issue with the Thon case itself, but rather with using the 3M industrial velcro. You really have to pull to get the industrial velcro to come off of the felt. Just make sure when you put down your pedals or machines that they will be there to stay because although the velcro isn't permanent it is difficult to separate your machine from the felt as it should be.
The only thing I could see Thon doing to improve would be to offer custom case sizes, but the cost would of course go up. Overall, the Thon case is a solid buy and one of the best values I've come across. Bravo Thon and Thomann!