Let's cover class specific trinkets first because they are in a pretty weird spot. Some of these trinkets are worse versions of the worse versions of a trinket that's mentioned for example, Tough Ring > Heavy Boots > Defender's Stone (not mentioned) > Protection Stone (not mentioned). Trinkets that aren't mentioned in this guide are probably not worth using unless they are your only option. This guide helps you identify the best trinkets and help you prioritzie quests in order to get the best trinkets.
While trinkets don't make or break the game early on, it definately helps to have your heroes properly geared for a dungeon. It sounds huge.Darkest Dungeon has a lot of trinkets and that makes the game daunting for new players. The wait may be worth it, though, as Chains of Domination adds a new raid, new mega-dungeon, new subzones in the Maw, and a ton of new story quests. Blizzard hasn't said when it will release yet, but my guess is some time early in the summer. 9.0.5 is strictly a systems and balance update meant to address some ongoing problems, but players are going to have to wait a lot longer for Shadowlands' first real update, Chains of Domination. What this patch lacks, however, is anything in the way of new activities or goals to pursue. Every player will also get a new mount that was made based on input from the community: A giant, wandering Ancient (think Ent from Lord of the Rings) whose leaves change based on what zone you're in. The official patch notes can be found here, but the patch also introduces a ton of tweaks to different classes and their respective Legendary items, as well as general fixes to all sorts of different systems. That's not the only thing coming in 9.0.5, though.