I don't own The Bard's Tale IV, but I have played a lot of Wasteland 3 and I can say is an awesome game, very replayable, with complicated moral choices that actually affect the game, many different situations and approaches to solve the different task, and a great role playing aspect. The soundtrack is really good, the graphics too.
If I have to say one bad thing about the game is that could be really easy, the challenge is really low in comparison with Wasteland 2, feels more "casual" but they added an option to increase the requirement points for special actions. I can definitely recommend the game, I pre order it and totally worth it.

I played Bard's Tale IV and liked it very much. I found the combat system quite fun and the difficulty moderate, it's a while since I played it but i remember it being fair. My main criticism was that especially in the end they pile up puzzle after puzzle when you just wanted to head forward to the final boss. You should be aware that there are plenty of puzzles, more than you'll find in Legend of Grimrock, what is similar to BT4. There is an item that you can use that should solve a puzzle for you in case you're stuck or just want to head forward, but for me it didn't always work.
Bard's Tale was never famous for their stories, so don't expect too much. They included some references to the original series, in case you played them.

I had fun with it and would recommend it.