I don't usually like or bother with reviews but I think this game is incredible enough that it deserves one, and it might help someone who is on the fence about giving this whole rhythm game thing a try.
DJMAX Respect V is very polished, has a great original soundtrack, and a bunch of modes/difficulties that are fairly welcoming to complete beginners but still offer a high skill ceiling.
To go into more detail:
There are four play modes that indicate how many buttons are used: 4B, 5B, 6B, and 8B. Each of these also use two extra 'side track' buttons, so it's more like 4+2, 6+2 etc., but those aren't used too often in most charts so they don't add much complexity. 4B should be playable for anyone and is a good entry point.
Base game has about 160+ songs. Each has separate charts for every mode, each with 2-4 difficulties, so there's a ton of charts to play at any skill level.
In the future, there should be many more songs coming in DLCs (afaik some will be free updates, but most will be paid) that will restore the soundtracks from previous DJMAX titles. On PS4, there have even been extra collaboration DLCs with Guilty Gear, Girls Frontline' and League of Legends music, though it's unclear what will be coming to PC.
The music itself is great, and even though this is as subjective as it gets, I think I can say that anyone should be able to find something they enjoy. Also, a cool aspect of DJMAX is that in most of the charts, hitting the notes is what produces the sound of the song's instruments, which makes the game very satisfying.
Respect V is primarily meant for keyboard(and similar controllers). While the previous version, DJMAX Respect, was on PS4, Respect V adds new charts that can only be played on keyboard. However, those are considered to be of an extreme difficulty, and if someone prefers, they probably could play on pad.
The developers are still actively working on the game; right now it is being patched quite often, and they're planning to add more online features, including a ranked ladder mode. Right now open play lobbies are already available(in a beta phase), which is a nice way to play through the songs with others.
On the negative side, there are two relatively serious technical problems with the game. It includes an invasive rootkit-style anti-cheat system, which can put some people off. More worryingly, it's also an always-online game, which means playing without an internet connection is entirely impossible.