You'll need to pre-plan your corners to get the boards matching correctly. Depending on where the V-grooves fall it could look a bit odd. Remember, you'll have the 100mm width of the board and then two corner angles, so depending on where the V-grooves fall, you could offset the board's position. I think it might be best to start your boards at the corner and work around the room from there. - MitchellMc
I suggest using 1.5mm aluminium angle trim instead of timber simply because it's so much thinner and more seamless. You can see this in a recent project I completed. Just prime with an aluminium Etch primer before painting to match your panels.
Depending on the overall style you're going for, Easycraft offer a Made To Order option of 63mm grooves (which I used on a recessed TV wall) which offers a more modern finish and may be better for what you're trying to achieve. - ProjectPete