The problem with most of these is: without proper training, you won't be able to use most of this stuff properly, and you MAY do more harm than good if you try.
Not that it's a bad idea to have the equipment; someone else may be with you who's had the necessary training, and there's no reason why YOU can't get the training yourself (EMT-level, not brain-surgeon level).
What most of these kits lack is the (non-combat) basics: Band-Aids, Neosporin, and bandage tape. Be sure to add these. Also add things like sunburn cream, space blankets, Asprin/Tylenol, ACE bandages, and an eyewash kit, or at least some Visene. It's far more likely that you'll need that kind of stuff, and very unlikely that you'll be stitching someone up in the field.
-Troy