Clerics have few feats to spend, and a lot of attractive options. Imbued healing looks flavorful and interesting, but certainly not overpowered.
The paladin's Battle Blessing is OK, but not brilliant. The paladins spells just aren't nearly as good as the clerics, so comparing with Divine Meta-magic is misleading. Sure, it makes his spells more useful, but you get very very few each day, and you need to choose which ones in the morning (which, considering the few you get, is quite a limitation), and they're rather weak at the level you get them at. The feat doesn't grant extra spells, it only allows using them in combat (something a paladin is otherwise very unlikely to do). It's a well designed feat, providing something interesting that some may take, while certainly not breaking game balance.
These two feats are good examples of well-designed feats, being true options - not so good as to be must-have, and useful enough that some people can make good characters with them. These are exactly what a feat should be!
Holy Warrior is definitely less interesting. I don't think it's quite as bad as Nifft makes it out to be, but I'm not familiar with non-clerics - are there classes with nearly full bab which could use this? As is, it's nice, but it does mean you have to limit your use of War domain spells (which is unfortunate), and the feat must compete with seriously good alternatives, which means it's not a must-have feat. Then again, I only really ever play up to 11,12,13th level, at which point this feat isn't earthshattering. I'd assume that by the time you can cast 9th level spells, a +9 on damage isn't game-breaking, but I don't know about it. Certainly many divine feats have more potential for abuse.
I think these feats are what feats should have been like in the first place: Interesting options that allow you to differentiate your character from others, while being close enough to each other in power to make the choices difficult.