The game is quite enjoyable and will be worth it for you IF you take in account that this Mass Effect is not a continuation of the original trilogy, and that the protagonist is a completely new character on its own and not trying to copy/impersonate/be Shepard.
The game might have some annoying characters but you also have interesting ones and fun loyalty missions. After the main questline you may finish sidequests you didn't finish (No loyalty missions tho).
You can visit a bunch of planets (Way less than 100, let's be honest), but it's still worth it, specially if you travel in the Nomad and you hear your squadmates' party banter.
As for weapons, you can upgrade them by spending research points (initiative, Angaran, Kett research points, I think there are more but can't remember). By spending this points you can acquire more armour and weapons or upgrades to the "next level" of certain weapon or armour. You also attach mods (found or bought by you) to enhance them (Like you asked, better scopes, mags, things to improve recoil etc).
I understand why some hardcore fans hated the games and the new gameplay changes, but as someone who loved the original trilogy I loved this one too, and I'd recommend it.