in the campaign I'm playing in now "Against the Giants", I'm playing a level 5 gloomstalker Ranger/lvl 5 assassin Rogue/lvl 2 Fighter (lvl 12 total).  I'm a Fartraveler background and a Half-Drow.  My stats are as follows:  Str: 9, Dex 18, Con 15, Int 8, Wis 16, Chr 9.  Under the Ranger fighting style, I picked Archery, and my level 4 feat is Sharpshooter.  Under my Rogue levels, I picked Stealth as expertise, and I have Elven Accuracy for my Feat.  I dipped into level 2 fighter just for the Action Surge.

My weapon of choice is the longbow and I have the Amethyst Dragon's Wrath Longbow (Stirring) which does 1d8+5 piercing plus 1d6 force damage on every hit.  I'm also wearing both the Boots and Cloak of Elvenkind, which gives me advantage to move and hide and gives disadvantage to be detected by Wisdom (Perception) checks.  I have a +12 to Stealth.  My party consists of a Light Cleric dwarf, Palalock Asimaar, and Bladesinger Human.  There's usually a 5th player joining our game, but the last two weeks, hes had Covid so he's had to miss.  He's a Sorceror/Bard Gnome. Seeing as the Dwarf and Asimaar are both in full plate, our group is as sneaky as a brass band walking down the middle of the street banging cymbals.  But on most encounters, I'll sneak ahead of the group a good way and scout out the lay of the land and report back to the group.

I'm usually the first to go in combat order with me having an iniative of +9.  Most of the time, we dont get suprise because of the layout of the maps, but a few times I've been able to get off my full Nova attack the first round, but even without surprise, I'm still doing decent damage.  I just wondered what everyone elses thoughts are on my build.  Over on Reddit (I know, why Reddit trolls first), I'm getting blasted for my "super cheesy build that is only good for one thing".  I figured I'd rather hear from the DnD community to see if there is any suggestions or maybe some helpful advice.  I do plan on getting Alert and Piercer as the next two feats to beef up my fighting style.

If your having fun with it that's the important part.

If your table gets annoyed by it, you are less likely to have fun and it's not good overall. You and your group are the important parts of play. Forget internet haters.

Opinion time:

I as a dm/player prefer narrative multi-classes. I find breath of options by multi-classing but burn out faster. Long combat days are harder.

The other thing is I find more depth by playing classes longer. New spells or strategies cover perceived benefits from other classes. This mode stretches my creative ability to play out solutions only present in a role-playing game.

What Roscoeivan said basically.

Ill only add that yes, gloomstalker/assassin/fighter is a very known combo for very high nova damage in first turn... But in normal play it also fulfills many options, as long a you and your party give it opportunity, as you have done (scout, stealth guy). Play your skills wisely and just look for more sinergies with the party. If your group enjoys, then keep playing as is. Your party is basically very balanced.

The only other advice is keep your options open, in class levels all of fighter, rogue and ranger offers many good things (more expertise, prof in wis saves, fighter subclass and feats).

I've seen people telling me to go to level 3 Fighter for Battlemaster, but honestly, as a very heavily ranged type ranger (think like a WoW Survival Hunter), the Battlemaster seems a bad choice vs Arcane Archer.  With a Str of 9 I'm not doing a metric crap-ton of damage in melee.

But my party is absolutely loving the way I have my build.  They enjoy the sneaky secret squirrel aspect of my character and will stay back enough that even when I'm sneaking if they are detected, I'm still usually hidden and dexterous enough to get off an assassinate attack before the giants get one.

Don't forget, Battlemaster still has some really good maneuvers for ranged combatants. Precision attack makes your sharpshooter shots more consistent, Trip Attack and Menacing Attack give some good CC, and Ambush helps you make sure you get your Assassinate abilities even if you roll poorly on initiative.

But wouldnt a Trip Attack give ME disavantage.  So I go from rolling 3 d20s to just a flat d20.  Besides for our Paladin, the cleric and Bladesinger do a lot of ranged spells as well, the cleric especially uses Toll the Dead a lot, not sure if a Prone enemy would give Toll the Dead disadvante as well but wouldnt want to be the reason to give another disadvange. 

I agree Ambush is good, but even at a level 3, isnt the manuever dice just a d6?  So it would only give an average of +3 to Initiative.  I see Menacing Attack and I had read it as a melee attack, but now I do see it just says "when hit with an attack", so that one isnt a bad use.  I just think the Arcane Archer shots would give my attacks a bit more flavor attacks, especially Shadow Arrow and Grasping Arrow.

I really like disarming attack assuming you can get someone to collect whatever is dropped.

It also works for grappled allies.

Many of the fighter subclasses works.
- Battlemaster is just the most common for all the options it has, even for ranged characters. Besides ambush as a failsafe, and precision strike that synergizes well with sharpshooter, many of the ones that causes a condition or a ST are good. Its just a good all-around subclass. Choose the maneuvers that work better with your team. Even trip attack, it may give you disadvantage but it gives advantage to your melee comrades (i see its not always the case).

- Arcane archer its thematic and also gives you some interesting options, that differ from battlemaster. Even champion offers simple but good benfits.
- Samurai gives you another advantage switch 3 times per day. Its very good depending on your use of bonus actions and how easy you get advantage on your attacks (probably not as usefull for you, but just a consideration).

- Apart from fighter, more levels of ranger and rogue offer many other benefits every level too, so consider that. e.g. Gloomstalker 7 gives prof in Wis saves, ranger 9 3rd lvl spells, rogue 6 more expertise, rogue 7 evasion, etc

Toll the dead is not a ranged attack, just a WIS ST.

I like it, especially if you got primal awareness.  If you didn't get primal awareness, you probably don't have enough spells for my liking, but still a cool build. 

You should get pass without trace, that will give your Paladin and Cleric good sneaking rolls.

What is your fighter fighting style?  With a multiclass Rogue I particularly like superior technique with quick toss as a second fighting style.  This gives you another sneak attack option if you miss with your action or need to cast a spell or do something else with your action.  Darts will also work with both sharpshooter and quick toss.  Getting another level in fighter for battlemaster can get you maneuvers too or a level in Eldritch knight can get you cantrips and more spells.

Not sure what the Fighter's subclass is, he just joined our table last week.  I have Pass Without Trace as a spell along with Goodberry, Spike Growth, and Hunter's Mark.  As a half-drow, I also have Dancing Lights, Faerie Fire, and Darkness.  As a Gloomstalker with Primal Awareness, I have Disguise Self, Speak w/Animals, Beast Sense, and Rope Trick.  In my build, I'm more towards magic helps out my Ranger to do his job of pew-pew-pew, so I don't use a ton of spells unless its either Hunter's Mark.  Once I used Spike Growth because our Wizard had a Rod of Fear, and I dropped Spike Growth down behind a pack of 6 Winter Wolves and a Frost Giant, and every one of them failed their save so they all ran smack through the Spike Growth and took 8d4 worth of damage cause the Fear from the Rod didnt break on damage