Man, definitely the most different Halo out of the ones ive played. Stuff its famous for it really nails, the music is cool and relaxing which you think wouldnt fit an FPS game but it really works. The story is also fun as a side story in a bigger universe which, imo, makes the ODST more interesting than the larger characters in the universe. Nathan Fillion as Buck is cheesy but in a good way.
My only major issue is combat isnt fun. The overworld map is big and kinda boring with patrols of grunts and brutes every now and then with a few minor side things to do but its not very interesting. The actual flashback missions of the story are better but not by much, guns feel WEIRD in ODST and im not sure why? Maybe its how tanky brutes get or how ass the silenced SMG you get can be. The game feels like a gauntlet and not in the best way.
However for the vibe of ODST, id say its worth it, its a very unique game in the series and in a weird way, despite its combat flaws its the most memorable for me.

Very fun concept! Clear inspiration from Roadside Picnic/Stalker only with a beat up old woody station wagon as your best friend. The mechanic....mechanics aren't intrusive or too complicated so you don't have to be a car enthusiast to enjoy it, the car is very modular in that fashion (put the wheels on the rotors, put the engine in the engine bay etc). The world is fun to rip around and explore and the anomalies are varied and interesting to encounter. The only things that irked me is sometimes the writing doesnt always land but it isnt awful. Death can be quite punishing as theres no saving mid-run (you have to do a corpse run to get whatever shit you had in the trunk back.) Overall very relaxing ""rogue"" type game that succeeds in that feeling of falling in love with your piece of shit car!

If you are familiar with Owlcat style RPG's, this game follows the same beats mechanically. This includes the positives and negatives such as a great in-dialogue highlighting system you can click on to give you info on obscure lore (very handy for any 40k newcomers). And a bit of a clunky leveling system. However they definitely get the vibe of being a Rogue Trader in this universe, the characters are all interesting and fun. Its a bit buggy under the hood so expect some goofy shit to happen from time to time but the devs seem keen on fixing important stuff. If you like 40k and enjoy Owlcats Pathfinder series, id definitely recommend!