My opinion as follows:
On the face of it, I don't hate it. I just feel like the Clippers are getting way too little here. Blake is, to them, what Pierce was to the Celtics -- a homegrown talent they invested in and who stayed with the franchise back when it wasn't at its highest point (and some could make the case the Clippers reached their lowest points during Blake's early years).
CP3 isn't getting any younger, so if GM Doc deems to trade Blake, he's got to get back someone who can:
A) Help Paul, Reddick, and Jordan this year and next
B) Have long-term potential to take over as the face of the franchise
C) Fill a need
On the face of it, thanks to Denver's inclusion here, GM Doc does get A and C. Barton and Faried both fill needs -- Barton giving him a young SG/SF to use that's a huge upgrade over Pierce or Wesley Johnson and Faried fills in the the slot at the 4 vacated by Blake.
But Barton has already exceeded any expectation of him and further development -- into a fringe all-star perhaps -- is unlikely. Faried is a good defender and glass eater, but his offensive game is more limited than Blake's and starting him and Jordan together would absolutely murder any spacing the Clippers would have. You stick Faried or Jordan in the post and the other has to vacant, rendering their best skills far less effective.
Bradley is a nice get -- but ultimately redundant with Reddick there (though Bradley is the far superior defender, he's not nearly as prolific as Reddick is from deep) and, as a sixth-man, would excel but is fighting for minutes with Crawford and Rivers; you can't put all three out at the same time (Crawford would be eaten alive, Rivers is effective but inconsistent).
Ultimately, I don't see the need for the Nuggets in this trade. Would they like to take that contract they gave Faried back? Probably. But does it matter to them? No. Most of their players are signed to cheap deals and are young. Cap space isn't hurting for them right now and, when it does, Faried's deal will be off the books. The 1st rounders are nice, but what good does that do them? They don't need more 1st rounders, they need a star. Is Mudiay that? Maybe, but he hasn't proved it yet. Denver, much like Boston, has a number of cheap, young assets under control for a few years that could develop into something. But they simply don't have an asset you're really excited about, except maybe Jokic or Nurkic, but those being bigs means that the Clippers shouldn't care.
If you eliminate Denver and make this a straight trade between the Clippers and Celtics, you make a much better case. But then that's still not quite enough, because Doc doesn't get anyone to be the franchise face of the future. So you add in Brown -- it's either him or a Nets pick, and if I were Boston I'd ship him way before the Nets pick. The Clippers would want Brown over a pick anyway I think seeing as he gives them something in the now AND in the future.
To Boston: Blake Griffin, Paul Pierce, Alan Anderson (Filler)
To LAC: Bradley, 19 1st from MEM (from Boston), Amir Johnson, 18 1st BOS, 19 1st LAC (from Boston), Jaylen Brown
It's a steep trade for Boston in terms of future assets, but considering they have the Nets picks, these other ones are nothing. Doc gets back Johnson -- a 4 that has a little range and, more importantly, gives the Clippers some cap relief next summer when he comes off the books -- and gets Brown, who'll instantly start -- and a bundle of picks in 2018/19 that he'll need to either A) reload around CP3/Jordan or B) rebuild after both leave.
In either case, Doc is in good position. The Celtics get their new star in Blake, their old star in Pierce, and someone to sit on the bench to play in emergency situations in Anderson.
I feel this is the most realistic trade for Blake between these two parties.