I have to say I'm disappointed with Warband. I put my faith in TW and pre-purchased it and it feels like a waste of money now I've played it enough.
The multiplayer doesn't interest me because it's very, very underdeveloped and in my opinion sloppy with many issues that are fine in SP but when exploited by players online it's real bad. It's very barebones in any case, just a few basic battle modes and constant respawning with no organising in the teams. It would have been cool to be able and run a semi persistent campaign world, similar to Dungeon Siege or Freelancer, with players running about doing their own thing and occasionally interacting if they wish (maybe even competing to be marshals in the same realm or for the heart of the same fair maiden, complete with duels etc) alas they did not attempt any of this and imo took the easy way out.
The single player has some additions but few of them haven't already been done by mods, even if they're ever so slightly better here (like the morale, which in the user made mod causes enemies to run to the edges of the map, while in Warband they actually exit the battle map and form into a new party that tries to flee - though in the mod it seems to happen more often and more realistically, not just when there are too few units left to matter as in Warband).
In any case, it won't last as long as the first game since progression through it feels much the same with the same skills, the same battles, the same armor and weapons aside from a few additions which aren't even top tier items and will therefor see little use (like the Elite armors which have similar stats to the Heraldic mail armors, give or take a point or two, yet are heavier, or the new Sarranid faction's swords).
It's essentially the same game with a few enhancements that aren't beyond the scope of mods (or version numbers), and overall has lesser scope than mods like Sword of Damocles do. It's quite absurd that people are asked to pay more or about as much as they paid for M&B, especially in Europe (I paid $25 which at the time was like less than 20 euros, Warband cost me 26.95 euros with the 10% pre-purchase discount which today is $36 or so) for this thing.
They didn't expand the tactical aspect within battles in any real way (the AI still just rushes to you giving you little time to position your units properly, even though you can now assign troops to custom battle groups, not just infantry, cavalry, archers, etc), and while they did expand the kingdom management aspect it's not beyond fan mod features, while the way some things are currently broken (garrison wages, tax funds, etc) it's not even worthwhile for players to own many fiefs.
The graphical improvements are also minimal at best, the game is still ugly with crude models and low resolution textures, it just has the addition of crude basic normal maps and HDR now, which don't help the overall visual quality. Fan mods like graphical enhancement, polished buildings and hopefully soon polished landscapes did far more to upgrade the visuals of M&B so TW's efforts were a total waste of precious resources that should have been put into tangible game features and fixes.
My advice to every owner of M&B is to wait for a price cut, by Christmas it's probably going to be on some Steam deal for $10 or less. It's worth about that much as far as new content goes, unless you really want to play multiplayer or something, but imo that will get old very fast even for those who like it and it will be up to mods to offer actually compelling game modes that go beyond its simple barebones content. I made a mistake, feel free to laugh at me but be warned.
For new users however, Warband is the version they should get, and they'll get their money's worth with the playability of a grand, unique game, though they should still wait a month or two for the bigger issues to be resolved, if they are. It's just a shame long time supporters got fucked over like this. This is essentially Warband v2.0 Beta (there are loads of issues with the new mechanics, as well as issues existing since the original M&B they've yet to fix) sold as a full new stand alone product. I'll not be supporting TW's next project if it's similar (and With Fire And Sword is similar or worse by what I've seen of it, but I suppose that's not strictly TW, though they did whore out their engine and what not and allow them to sell a product that's an M&B mod at best, much like they're doing with Warband).