See my sig for the handbook.

A lot of what it comes down to is that when you're looking at divine casters, the Cleric, Druid, and Archivist are so good. They're 3 of the top 5 classes in the game, and there's practically nothing that a Healer can offer that tops their flexible spell lists (cleric/archivist) or excellent class features (druid).

The Healer's weak point is its tiny spell list. With a little adjustment, like adding the recommended Spell Compendium spells to its list or adding the BoED spells a Healer gets, the Healer is fine without being overpowered, much like the Dread Necromancer or Beguiler.

Just my opinion (and as the guide writer I'm both informed and biased, I suppose), but I think the healer is better than most people give it credit for, as long as you play intelligently. Out of the box and with 1-2 extra sources, it's better than the monk or samurai or most "T4" classes, and this is something that I've argued with JaronK over before.

A lot comes down to playstyle however - a Healer will be useful in a low damage game (since healing will keep up with damage) or a game that has a lot of status effect attacks like fears, poisons, level drain, and paralysis.