Honestly, the game only really takes off once you start taking part in the economy, buying the uniques you need for your build to work, and selling the useless uniques you get, all by trading with other players. It makes all the difference in the world.
Having at least one premium stash tab really helps a lot with that, and it's arguably the only thing you actually need to purchase in the game unless you're into cosmetics.
Character progression has a few spikes, that happen when you get Ascendancy classes, Keystone Passives on the skill tree, or finally get to equip an unique that is central to your build.
The game is really not easy to get into due to the massive amount of content that's out by now, but it's worth it.
I suggest you stick to pre-made builds until you're comfortable enough with knowing the game to start doing things on your own.
Once you get the hang of it, you can level a character really, really quickly and you'll be enjoying the game much more.
Also, the game wiki is your friend. Use it, really. I have like, 2000 hours on the game and whenever I'm playing I still have the wiki open all the time.