I hadn't tried it in 2 different playthroughs because it's rated really low online. But since I've used the other builds already, I figured I'd give it a go for Astarion in this new playthrough. He has an item that makes him invisible for two turns whenever he kills someone, which basically makes him a one man killing machine. For 3 different battles now I've split him off from the group and sent him out ahead to sneak attack the enemy group. Welp, reinforcements were never needed. He sneak attacks from range, turns invisible, moves away so he can't be detected, and attacks again. Each attack one-shots his victim, and he can make quick work of entire groups of enemies.
I can see that this build wouldn't be great for unexpected battles, or outright confrontation, but when you know that you want to fight, dang man! It's amazing.
If you happen to find that item that gives invisibility on kill, then I highly suggest getting a good bow, and giving assassin a try. It seems like it would be a good option for a playthrough without companions, as long as you are able to get back into stealth after attacking.
That's the rogue class in a nutshell. They're the party's swiss army knife. Bard is even moreso, but with less damage unless you dual class. Bard 9/Paladin 3 is probably the strongest build in BG3.
This looks very fun! I also would like to try Bard/Barbarian for multi-hit and raging in battle while singing !
If you go bard, make sure you take the sharpshooter talent, college of swords, and keep an eye out for the hand crossbows. There are only a few of them in the game, and you need two to make the build shine.