Is +atk/-spd brave Roy any good

Well....he certainly won't use Desperation much....

In this case, you basically have something closer to Regular Ike stat wise. The difference is you swapped the a skill and sword passive technically. depending on how you go about his team comp, you can run him much the same but without the distant counter unless you have spare hector's laying about.

In this case, either Swordbreaker, or QR2 and the a skill is likely best as Fury to add more bulk and slightly offset speed, reducing who doubles him by a nice amount.

He can be used yes, and will mostly work as a more mobile Ike (especially with distant counter) but he will likely feel fairly underwhelming compared to his ideal form with +Spd.

My Brave Roy is +Def -Spd and I thought he was not that good at first. I was using him with darting blow and swordbreaker, and he was just OK. Then, I decided to give him Life&Death3 and he became a beast. He has 36 spd which becomes 42 with hone cavalry, 43 with spd seal, and 45 with S support, which is enough to double and use desperation. His attack is already sky high with neutral atk + hone cavalry, and your Roy can be even more powerful with that boon.

-spd is really crippling for Brave Roy, and definitely is his worst bane, BUT with L&D3 and in a horse emblem team he is extremely powerful, especially with Atk boon.Your Roy is more than salvageable if you decide to invest in him. Best player phase sword cavalier by a mile, despite spd bane.