I'd say keep the button layout as it is if you're planning to release it for others to use, as it's not a rarity for people to require even more buttons than you have showing.
Only suggestion I'd have is changing the position of the target frame, seems rather random. I'd put it ontop of your health frame, making the target buffs/debuffs show on top.
Apart from that, really nice work. Looks very clean.
