The Blues are perfect at doing the critical task of rounding off the top end without getting muddy. They kill the fizz but not the clarity. That's what I love about them.
The only con as far as I'm concerned is the power handling. Supposedly they have a flabby bass response, but I haven't particularly noticed it. I think most of the complaints seem to come form the drop-tuning crowd, so apparently they're not for metal. That being said, I have no issues putting the high gain to them.
For the brightest smoothest top end nothing beat the Blues [Webbers aren't close]. For more bottom and slightly less top the Scumnicos sound killer, Beano all the way. For warm and smooth even less top and more bottom the TT Hemp Alnicos. I have tried all the budget alnicos they always sound well budget in comparison.
If power handling is a problem, try the Gold. Near as dammit to the Blue tone, takes 50 watts. Both are incredibly sweet, detailed, smooth on top but chimy. Seems a contradiction but somehow they make it work.
I have an Eminence Alnico Red Fang in my Vox AC30 and it sounds amazing. It depends on what you're playing through, but through the Vox, it's definitely not a $100+ tone difference in my opinion. Again, depending on what your style is, but the biggest "con" I saw with the blues was clean headroom. To some people that's OK though too. Personal taste I guess.
I like Blues, but the prices have gone up and I am going to try a Warehouse Black & Blue Alnico (I ordered it a fews days ago and will post findings soon).
There is a company in Austin that rebuilds new Blues to their specs, so they are pricy and I have not tried them yet.