Tamriel rebuilt is not that fun.
There is no connectivity with main island, even travel, which doesn't look like Morrowind general design at all. They didn't use one of the game's strongest points.
There is no overarching plot either, which is even wierder, you'd think you should have either this or that, like in Tribunal, but you get neither.
If you're not telvanni master race you feel left out.
Starting quests suck ass. They make you go through beginning of all the factions again and gather wickwheat and such. Not all quests are bad but what was new and felt right for a beginner in Morrowind is just a chore here. Aka "we couldn't make any good ones so go gather these ingredients".
Lots of unused space. Big distances between big settlements that are actually interesting.
It's clear modders were afraid to outdo main game in any department, especially loot, so they ended up with content which is like original, but feels weaker and bland. Especially shows in loot - if you got your devil weapon from Ra'Virr, you're set. And that's with me using alternative leveling mod (some new version of old Galsiah's Leveling), which halves my power level - my 25 level character is weaker than something I could built in regular Morrowind on level 10 (around 75 points in spear & bows and 50 medium armor, 60 STR & END and no magic skills).
There's some new good armor but only if you don't have anything better low-tier armor from Morrowind yet. Like in Port Telvannis I got this best bitchin CHIM armor aka full dreugh set.
Everything does look good and terrain is nice, some nice dungeon designs too, but it proves that most modders can into tool set, but can't write interesting stories.
Also combined with Overhaul some locatons like major cities give me like, 12 fps. Heh.
On the other hand, I also installed Less Generic NPCs which is absurdly fun. It makes game more fun to read, sometimes expanding on characters well, sometimes adds new quests, sometimes - generic boring crap like item collection, and sometimes it delivers massive bioware derpness which somehow feels like it could belong in Morrowind. It often dumps a shitton of lore aka PoE backer NPCs "i had no mom and dad i became [class]" so it's a mixed bag but it is worth it. This mod + visit to Tel Mora made my weekend. Or how I would call it now, a Telvanni Tower of Unresolved Sexual Tension. Sure sure, there's a quest for healing one from infertility with a help of daedra heart and kwama egg and testing it out, but that's not the best, in my opinion best part is Dratha stoically hiding her being enamoured with big man Fyr, but she just can't work with him because he is such a swine who made that clone harem for himself! Gold.
All Abnaxus's fucking fault for making me spend whole day to mod that shit again and make it work.