Essentially, i have what's just about a complete build, including FCOM and all those goodies, and now i'm wondering whether or not it's at all sane to try to install UL at this point since it has a lot of compatibility issues to keep track of.

Compatibility isn't a huge deal, just check the page on the nexus. Go down the list and download the patches for all of the mods that you use. I used to use the whole pack, but I recently took them all out in an attempt to improve performance. I think the better thing to do is just pick out the one you really want and just add some of them, or at least not all of them at once, so you understand them better. I actually don't think FCOM conflicts with UL at all, though there might be a couple OOO or MMM patches to get.

Yes.

That′s no question whether it′s worth it (unless you consider Oblivion as a mere - somehwat slow? - fantasy-shooter & don′t care about nice graphics and individual landscapes). Not a big deal performance-wise neither (no comparison for example with QTP3 and the like...). I use all parts apart from DarkForest, but that′s just because with my old rig (which indeed was very old & slow) that was the only part causing some stuttering, and it′s touching quite a few areas around the heavily modded western and southern shore of Lake Rumare/Imperial Isle. Shouldn′t be an issue with a rig that is not yet ten years old...So, performance is definitely not an issue.

One issue might be free esp "slots" in the load list, because AFAIK it′s not recommendable to merge the UL-mods (and that rat′s tail of patches) together to save space (even such merged versions exist for download - never tried them, tough).

I playtested UL-FCOM quite a bit (hardly do something else than installing & playtesting :brokencomputer: ), enough to say: No obvious problems occured. There are patches for all major mods, and the only real "problem" might be things as house mods, or those hundreds of less known, small do-a-little-something-mods. But even here, I only had problems with very old house mods from 2006 or 2007, and even then it′s quite rare. It′s surprising, given the quite large number of UL-parts & the quite large area they cover together, but to me it seems like many modders are well aware of the UL-parts & took them into consideration.
Basically, they′ve called it "UL", because that′s shorter (and less sounding like vomiting) than "UOLP" (Unofficial Oblivion Landscapes patch)....
Edit: BTW I didn′t mean to discredit DarkForest with what I′ve written up there - it′s just because of performance problems from years ago that I somehow never included it anymore in my builds so far...

More than almost any other mods that exist for Oblivion! That is how much it is worth it.

They were always among my favorite mods; they really helped bring the world alive with more unique regions and varied landscapes when out in the world exploring.

If you like them, go for it. Compatibility isn't a huge issue if you take care with patches.

The UL mods are a must in my book because the vanilla landscape, though beautiful, it gets pretty old fast and specially repetitive. I guess this is the reason why UL exist in the first place.

I have played oblivion vanilla on xbox for ages. I got a good gaming computer a few days ago, and honestly, with UL, better cities and OOO, this is possibly the best game I have ever played - it is actually almost perfect. So basically - yes, get it, now.

I say depends on how you want to play. I usually have them but not in my current game. I am trying to keep the esp count down (ULs and patches would take up half my slots). I am concentrating more on interior adventuring so the outside world remaining vanilla is plenty good, easier trek through wilderness to my destination. Besides, as beatiful as the ULs are, after seeing them for as long as I have, not as exciting anymore (but make sure you get to the special scenic places at least once, it is something to behold).

They certainly add to the feel of the game world, so if that is of interest to you then most definitely!
And there is now a handy Bain package for all the compatibility patches, with a wizard to automatically pick all the ones you need, making compatibility almost a non-issue.

I tend to cherry-pick those that either 1) will be seen most often by my avatar in the normal course of executing his daily routine, 2) add 'bling' to an area I find particularly bland, or 3) some mixture thereof.

My avatar spends to greater portion of his existence patrolling Cyrodiil's major thoroughfares. He does so almost constantly. He's not much on traversing the wilds, doing so only at necessity and rarely for pleasure. Therefore the ULs that most appeal are those that straddle a road or roads. Skingrad Outskirts, Bravil Barrowfields, Chorrol Hinterlands, and Imperial Isle (especially if one has NR+B installed) are good road-straddling ULs. Cliffs of Anvil, though it doesn't straddle a road, is easily seen when traveling to or from Anvil by road.

I found the Imperial Isle lacking in visual interest (discounting the Capitol) from day-one. That UL helps remedy that. I use it in conjunction with Region Revive - Lake Rumare, AFK_Weye, NR+B, and Verona House Bloodlines to make the Rumare Basin far more appealing.

Then there's Lost Coast. It most definitely can not be seen from a major highway. But the Gold Coast is another vanilla area I find lacking in visual excitement.

Those are the six ULs I run at present. I'm thinking on adding Rolling Hills to the mix at some point, and occasionally ponder another couple.

-Decrepit-

I've used them all but many have now been removed, some are just an unnecessary display of clutter and rocks all amassed in one cell, but a few are brilliant and really imaginative, it's up to tou to decide what fits your game style, my fav is Chorrol hinterland.