szilard said:
Remember, some illusions work perfectly well against mindless things.
Yes, and I did say that they "can't do much against undead, etc.", not that they can't do anything at all against them. Just very little.
Also, with UMD, a Beguiler can replace a Wizard if needed. I don't quite see your point about Charisma. Beguilers have less MAD than Rogues in my mind.
At the cost of many expensive scrolls and wands over time, sure. Whenever he can find a vendor nearby to purchase any scroll/wand he needs. A wizard doesn't have to shell out lots of money just to be useful on the occasional undead-infestation adventure. Or during high-level adventures where Mind Blank may be in use by the main bad guys.
Also, UMD doesn't apply much at low levels, where the Beguiler will have to deal with Zombies, Oozes, Monstrous Spiders, and Giant Fungi before he or she can become decent with the UMD skill. And he's got other things to spend feats on besides Skill Focus and suchlike, though he can if he wants.
They're not really more MAD-afflicted than Rogues, but they do really really need UMD if they're going to avoid MAD and do some damage. And even then it'll usually be with a relatively weak wand instead of an equal-caster-level Fireball, Magic Missile, Chain Lightning, or what-have-you. Unless they got money pourin' outta their ears and high-level spellcasters on their speed-dial for on-demand scroll-makin'. -_-
Don't forget that Beguilers have some nice buff spells and a bunch of battlefield-control spells. Even if their enchantments are useless in a particular fight, they can still be very useful in the hands of someone who knows their spell list well.
They have limited buffs, and limited battlefield-control spells. They're useful, and I've already said before that they're fairly powerful, but they're still rather limited in effectiveness. They can slow down the enemy or try escaping it, but if it can't be mind-controlled at the moment (or just has a high Will save), the Beguiler's about as effective as a Bard who's used up all their performances, most of their spells, and most of their Str/Dex from ability-damaging monsters.
The Beguiler's just too focused on being awesome in one area and only slightly useful the rest of the time. Too good at what he does for the rest of the party to do much in those situations, and too bad at everything else for when the rest of the party is active.