Well it's a season. Of course you get mostly cosmetics. In D3 you can get an extra tab for your stash but only if you complete the whole season journey, which eats basically the same amount of time and effort (as a casual player) like in Martyr. And do you need these extra tabs as a season-only player? Not really.

The hardest part is getting your char viable for 110 missions without dying. But you only have to do 3 of these. If you can do this you are good to go for everything else. 

Is Inferno any good and worth Console? No.

Seriously. Some Challenges and Tiers are HARDER then you should expect. And the only rewards is nothing but Cosmetics. But if you like nice cool Cosmetics, sure. Go for it.

And yes, you HAVE to start a brand NEW Character. And if it helps at all, then I am Lvl 95 by now myself. Others been reaching Level 100 weeks ago. But I was also focusing on doing some of the Higher Lvl (4-5) Tier Challenges very early on, and therefore did some HUGE amount of grinding VERY early on. So when I and IF I DO get to Tier 4-5 I do not have to think & worry about some of the Challenges. It is already done. Just to see and know that some of those Challenges are already done, is in fact calming.

Some people say: Have done it all already. Easy. Which it is not. Personally I´m not sure whether I am going to make it ALL done or not. How it is by now, I see myself as very lucky if I even get to finish Tier5.

And yes, I´m sure having no life with important stuff to do, is also very helpful. So get out your Bucket and go (Southpark) ALL IN. Lol.

GL.

There will be new enchants and items with the season update that boost XP by a lot. And there is a season task where you have to collect 2000 cortex fragments. Which means you have to play at least 10 weeks anyway (200 per week max.). So you can take your time. Some tasks will sound harder than they really are. It's all do-able with a little patience.

BUT prepare yourself to overthink your current build. There will be changes to dmg reduction and several perks so you have to care more about your survivability. 

The rewards are basically cosmetics (frames and some skull stuff for the command bridge) and favour points.

I think it was a great season (waiting for getting the rest of the cortex fragments).