So lets look at the Swordlord Prestige Class. Is it worthless? Not exactly. It will be great when the SCS-style mod that adds in pre-buffing/tactical play comes along since it's the only class that can turn off buffs and the effects of Bard Songs. Until then lets look at what we have:
No onerous prereqs that would be otherwise bad - you need the 3 Mobility to get 3 AC from Fighting Defensively and the other thing covered up there is Persuasion which is handy on a main character and ends up being required by the Swordlord class itself. It does take Persuasion 5 so you're not getting there until level 6, which can be a problem with:
Level 1: Deft Strike
Only other ways to get DEX to damage are via feat, agile weapons, or Rogue 3, so this is a solid full BAB level (most lvl ones aren't). Only problem is waiting until lvl 6 to get it since the first agile Dueling Sword is being guarded in ch 2 by some very mean Owlbears. Will get into ways around that in the builds.
Level 2: Display Weapon Prowess
As a non-offensive caster you can't afford to invest in jacking your CHR too high, and the bonus feats aren't going to be there to let you take a skill boosting feat either so this one is a life-saver to make sure you can clear skill checks in dialogues and function properly with later Swordlord abilities which require Intimidation checks. +5 from levels, +2 or 3 depending from Feats ends up being both good value and sorely needed.
Level 3: Defensive Parry
+1 Feats are meh and every level you spend in Swordlord is a feat you aren't getting from Fighter so this level is subpar.
Level 4: Adaptive Tactics
Effectively +2 to hit if you're using Fighting Defensively (which you will be) and Combat Expertise (which you usually don't, but this ability facilitates) and an additional +2 to hit and AC if you pass a Perception check (a skill you almost always want to stack anyway). This is a rock solid level and a reason to play the class.
Level 5: Shatter Confidence
Free Cornugon Smash on Crit or Disarm (see first build below) or if already Shaken another -1 to AB and Saves and loses Morale bonuses (Bless, Aid, Heroism, Good Hope) on Saves and attacks on anyone. OK but lackluster until prebuffing implemented then the heart of the class.
Level 6: Saving Slash
-25% crits. If you build well you'll be in 1 in 400 crit territory by midgame, or 1 in 20 if you're using Harrim's Destructive Aura. On Unfair that one can kill you if you don't have Image. This makes it 3/1600 or 3/80. Not a fan of these mechanics but does reduce reloads, enhance survivability.
Level 7: Dexterous Duelist
Don't provoke AoOs when standing up from Prone. This is one of the ways you die, especially if you're a Grease user. By the time you get this you've already left most of the wolves behind tho. Add in another +1 AC from Parry and it's a barely passable level. Full BAB for all these levels does help though. If you actually level up a Swordlord through a playthough this is where things feel like they're starting to slip away as the other classes gain all sorts of cool abilities.
Level 8: Adaptive Tactics 2
Another effective +2 AB full BAB which is a solid level
Level 9: Saving Slash 2
-50% crits. Things getting thin here. One shots are your Achilles Heel, so guess it could be worth it.
Level 10: Shatter Confidence 2
Another -1 to Saves and Attacks, plus canceling Insight and Competence (Bard Songs/Barb Stances) bonuses. That's attacks against anyone and saves against any spell or abilty so better than it looks (effectively a group buff), but not worth it until you get pre-buffing/enemy Bard Songs.
So to sum up at this point a solid 4 or 6 level splash for a unique, lore-friendly experience, or all ten if you really need the crit dodging or you're playing a sweet SCS-style mod in the future.
First build to follow.