I've been trying out a few mods for the first time recently, Oscuro's Oblivion Overhaul (I tried it briefly before but had to sop due to a glitch) and
The Lost Spires.
Much has already been said about OOO and all I'd add is that IMHO Francesco's is better thought out and definitely preferrable. Two major problems with the mod for me, one is that no thought was given for balance in respect for a new character, and especially for a new player of the game. There are too many over-powered 'monsters' in the early part of the game, both on the roads, and in what should be starter dungeons. Not knowing what's around the corner is all very well and good, but with OOO it's all too likely to be a re-load, or at least a dead citizen or legion soldier or two. The vanilla games diabolically bad AI and scheduling are bad enough, OOO makes it even worse.
The other main problem I had with the game is that by preference I like to play mages, initially I thought OOO had made playing them difficult and that magic had been nerfed. Oh how wrong initial impressions can be. Once one gets the hang of the changes Oscuro has made, and either have Frostcrag Spire or manage to fight your way through the recommendations (a lot tougher without Frostcrag, especially Leyawiin, watch out for that 24th level Bog Ogre!) it's game over. I had to abandon playing a straight mage well before half way as it was far too easy and boring.
Overall, if you're not playing a straight mage then it does improve the game, but check out Francescos as well is my advice.
I never got to the point of tackling The Lost Spires with my mage, well not beyond clearing out the initial spire when I was 5th level, but had I done so then my character would have been more than god like by the end. Whilst there aren't too many uber items for most characters for a straight mage there are a couple including being spoiled for choice in which robes & hood to wear. By the end though there is no choice, the penultimate Robes and Hood are just too much.
The only other item that stands out as over kill is a trap device, which frankly is too silly for words. You actually need this device to stand a chance in a couple of the boss encounters, but it doesn't disappear at the end of the campaign. It really should have a limited number of uses, unfortuately you can use it as often as you like, there isn't even limit on how many times you can use it in combat, which is really bad in the long run.
The final encounter is ridiculously tough, I wonder what the minimum number of reloads is for anyone completing it without exploiting bugs or glitches? I'd hate to try taking it on without the aformentioned trap device, you really do need to be seriously well prepared for this fight. In itself that's no bad thing, it's a bit too tough IMHO, but with preparation and persistence winnable. What follows that is completely retarded though, an insane deathtrap; to make things even worse when I finally got through the death trap the quest broke, the final stage didn't trigger. Fortunately for me I have no problem with the console so was able to setstage out of it.
Overall an excellent mod, kept my warrior amused over the whole week-end:
My character for the quest:
Race: Nord
Skills: Armorer, Athletics, Acrobatics, Block, Light Armor, Heavy Armour, Speechcraft
Birthsign: Revised Atronach; replaced the magicka boost with disease immunity, I lack self discipline so need to cripple my magic using abilities
I was about level 9 when I started on TLS, level 16 when I finished. Had I started at much higher level I think it would have been too easy, apart from the final encounter, and one other boss encounter.
One final piece of advice, at one stage in the quest line you ge t sent to check out an Ayleid ruin in the Imperial City, take loads of arrows with you if you depend on a bow and arrow (as I did), I started out with about 400 arrows, but was down to less than fifty at the end. There are arrows you can pick up en route, but not of very good quality. Also take along plenty of repair hammers, you'll need them!