Surprisingly good. Very clearly made by people who respect the lore, but who also have sufficient creative experience to know when a departure from the original material will make for better television. (I'd contrast this with, e.g. Aronofsky's _Noah_, which was a fun movie but made almost no effort to follow the source texts at all. I'd also contrast it, on the other hand, against religious shows that are basically the Bible in audiobook form but also with pictures -- which, based on some of the other reviews I've read here, is apparently what some very conservative evangelical Christians want from their television, which is a sentiment I find understandable but misguided.)
I'd describe the show, based on the first three episodes, as basically "family-friendly Game of Thrones". (I guess "family friendly" is relative; there's some blood splatter, but compared with GoT etc it's very restrained. I was a pretty sheltered kid, but even I would have certainly been allowed to watch it as an early teenager.) I will say, without spoilers, that on several occasions when the showrunners had a choice between a "safe" and bland option, or a weird and startling one, they opted for weird. That was a very good decision, as it makes the show watchable for people who (like myself) are very familiar with the source material as well as easily bored.
The show loses a couple of stars because there are a couple of shots that are slightly out of focus, and also the plotline of David himself is a little boring so far. (This might seem to be a severe defect for a show titled "House of David", but there's actually enough politicking in the court of King Saul, and other events happening, to make the show very watchable while I wait for something interesting to happen to David.) That might knock it down to 7 stars, but I'm adding one because I enjoy (well-made, not garbage) religious television in general, bringing the total here to eight.
Definitely better funded than other religious media that I've seen, such as The Chosen (which I also enjoy and watch religiously (hah!) but doesn't have the same production value in the first few seasons that House of David has right off the bat).
If you're Christian and enjoy television inspired by biblical narrative, I'd recommend it. If you're not religious and are just looking for a well-acted, (mostly) family-friendly historical action drama, I'd recommend it as well.
