So I've had my THR10 for a few days now and am really enjoying it. Yamaha have marketed it perfectly by calling it the "third amp". You won't be getting any heft or wall shaking SPL but putting a bass through it sounds like bass. I'm using it for what it was intended for - low volume practice - and for that it excels. I've found playing quietly through it at night with flatmates sleeping in nearby rooms is a more enjoyable experience than playing through headphones which can feel a bit disconnected. Though headphones will still be king for use with my pedalboard, especially since I'm a heavy octave pedal user. But if I was going to be bringing the THR somewhere with me I wouldn't bring a pedalboard anyway as there are enough effects on board to satisfy.
Not obsessing over pedals and just concentrating on a nice basic bass sound has already meant that I've focused on actually PLAYING BASS over the past few days. That in itself is a huge plus and makes it worth keeping!
Playing music through the Aux input is perfect for bass practice as the sound of playback isn't very bass heavy at all. Mids and highs are nice and overall it has quite a "wide" sound if that makes any sense. It's like it's deliberately leaving me sonic space for playing along with my bass. For pure music playback though, I'll be sticking with my trusty Bose Soundlink Mini. I'll keep that little magic box until my dying day.
In summary, the THR10 wasn't an absolutely necessary purchase as I have other practice solutions which can cover similar ground. However nothing I have does it quite as elegantly, or in as neat a package, as the THR10.