It has been a while since the last DLC, but it's not like it is an early-access game or anything, it's been fully complete since like 2010, and the base game has enough content for like 3 full games anyway. Other than the orc campaign, the DLC just add new classes and such.
Yeah I'm not saying it's incomplete or whatever, just that patches have stopped for a while, while many other roguelikes still constantly patch random shit in every now and then(DCSS for example gets patches every few months with new shit).
The game could also use bugfix patches, there's always a ton of known bugs, not necessarily major ones that break the game but that skill doesn't work with these items kind of thing.
One of the things Darkgod(main dev) teased in the next DLC patch too was a shorter more randomized campaign(rescaling of xp, dungeons that are available are more random instead of being somewhat fixed with a few optional dungeons being random kind of thing), leading to less fatigue from running the game over and over in roughly the same places(the dungeons themselves have randomized maps obviously, but all my runs pretty much followed the same route, and especially in part 2 there's very little randomization). Not having that kinda sucks too.
It is what it is though I don't regret buying the game(I even bought the cosmetics pack shit I never used just to help the dev a bit more since it was worth it) but it sucks it went that way, if they had kept up the updates like when I played the game would be much different today I think since they were patching like every 4-6months and it's been 3-4years of nothing. It is my favorite roguelike still though, I wouldn't have put that much time into it otherwise and whenever the DLC releases I'll definitely be going back to it for a while.
In the meanwhile there's a ton of other games to play in the genre so I've been going at them every now and then. Currently playing Barony which is an interesting take on the genre(it's real time first person so plays very differently but lots of similarities), and in may Path of Achra releases fully so I'll be going back to that, played for a couple of weeks in early access a few months ago, the guy patching this literally releases patches every day though so the game has a ton more shit than since I last played, also different take on the genre with even less things outside of combat(as in none at all, you just fight) and a simplified combat with shorter runs, usually 1hour or less per run. Caves of Qud has a planned release at the end of the year(likely next year though cause no way they don't get delays) so that's another one to look forward to I've been holding off until it's 1.0, and I'll go back to DCSS at some point as there's been a ton of changes since I last played.