They cost 10200 (not sure on the math; I just added the cost of priests [1800] to his, so it's probably right) dude. Priests are shitty as well.

I don't know, I've kinda changed my mind on this one.  Angels don't have anywhere near the straight, in your face, noticable impact of the other creep upgrades, but they do work quite well as skirmishing forces in several situations.  Sure, getting them in a situation where they're feeding right into a meat grinder is just helping the other team, but they give you a *much* larger line of sight which is a huge boost on big maps.  They also harrass enemy creeps (they'll do a decent job of slowing enemy giants until you can get your own as they keep getting distracted trying to swat them), and as was already mentioned they make using the heart of life harder.  The situational awareness though is what really makes them useful, when you're on a team that's actually coordinated enough to ambush enemy demigods (or playing against one!) having a general idea where all the enemy demigods are is a huge tactical advantage.  Even when you're not, it gives you the freedom to much more aggressively attack towers, etc. when you're pretty sure UB isn't about to leap out of the fog of war.

I think priest hp is good for the early game when you *can* get them. When your Demigod only does ~150 damage and it takes 3-4 hits to down them. They lose that when you get them later (which everyone does) and so they die quicker. But bumping up their hp would make them a bit crazier early on.

I wish Angels were a little more effective too.  Maybe 4 of them would be better, or they need a 25% dodge chance.

I also would like to see exclusive creep trees.  Something to mix it up so it isnt always the same thing.  Maybe one that focuses on seige and air, and another on slow heavy armor, and another on faster ranged units. 

Not that it justifies the purchase, but since it hasn't been mentioned yet; angels are excellent at harassing DG:s with a HoL. I've found that I usually have to put some distance between myself and the enemy base before using the Heart of Life.

I actually think that priests are extremely useful to your side for the constant healing you get from them.  They make pushing towers much easier and since they hang in the back they can even be a tipping factor in a DG vs DG encounter if they're nearby.  I would definitely have them at top of my "to get" list in a game if it were not for the unfortunate fact that they do feed so much gold and xp to the opposition.  Thus, they really are a double-edged sword.  This actually seems a bit strange since upgrades in general are about gaining an advantage over the enemy, not giving them one.

-dolynick