I finished Tainted Grail. Pretty good. If I'm being generous, I'd give it around a 7/10. It starts strong and gets linearly worse over time starting mid-act 2. There just isn't enough stuff: dungeons, spells, interesting quests, everything just falls apart and devolves into a bit of a tiresome and repetitive slog.
The "faction" quests in particular are a major letdown since there are no real guilds, guild-halls or consequences. Another big disappointment is the lack of a real city. The world feels very dead and stale, even if I like the art direction quite a bit. Something else I liked a lot was the combat, which (before your power level outscales the game) is very hectic and fast paced. It is amazing what something as simple as a dash does to the otherwise boring modern ES-style combat.
I do not regret my time with it but I'm not exactly itching to jump back into NG+. There was a lot of wasted potential, a large sense of "what could have been" if the game had been given more time and resources. But, I think what we got was good enough to justify its existence and the price of admission. If modders ever round out the game with some much needed content and polish I will definitely return to Avalon.
Edit: Forgot to say, every time I booted it up and heard that theme song I started chuckling. Its kind of a perfect encapsulation of the game, self-serious and trying to be epic while coming off as quite goofy. I'll take that over the self-aware reddit tone in modern RPGs any day.