.

I think all the single player upgrades are skins and stuff you unlock in the game through natural progression. Lost Adventurer is the only thing worth your time.

Lost Adventurer is just a very short puzzle, it adds like 15 minutes gameplay.

It's just a few skins and other pointless stuff, but it's also quite cheap... I'd rather it was on the original game and not on DLC, but whatever.

Also, Lara looks way hotter on the muddy skin.

Every upgrade as a DLC is worthless, because you get all that during the game.
Clothes for Lara are interesting to see her differently, but wortheless or not that depends from you personal opinion and interest.
Multiplayer items are wortheless, because nobody plays it.
"The Tomb Of The Lost Adventurer" DLC is better, because you can play something new, but again, wortheless or not that depends from you personal interest.

The game is good enough without anything more added to Single player ;)

You should get the DLC with the monkey pet. Also the one that adds nuclear arrows is pretty rad. And not to forget Bionic Legs DLC.

The tomb is the only one worth it, the rest are skins and skills you can get later ingame

I bought and played Tomb of the Lost Adventurer and it took me 20 minutes to finish.
Its just another tomb and it's even bugged without the developers fixing it (known bug, and luckily there is a workaround but still it sucks)
Tomb Raider is a great game but just skip all dlc is my advice

Not really, the additional tomb is very short and easy