No, as of the information we know at this particular time (two minutes past eight in the evening on 25/08/2011) we know the following about the Silents:
- in the season five finale we are told 'Silence/Silents will fall' - me, I think the message was gloating, and so the Silents are looking forward to the silence that may or may not have been the end of the universe. If we assume that the Silents were somehow responsible for the end of the universe, well, it was bad.
If we assume the end of the universe was a lucky coincidence then it could be that the silence is coming up in the next half of season six. Both of these options are based on the species/group (could be a cult after all) name and the fact that the voice that proclaimed 'Silence/Silents will fall' sounds similar to the voice of the Silent in 'The Impossible Astronaut'/'The Day of the Moon'.
If we assume the voice said 'Silents will fall' it's a prophecy. The Doctor doesn't really escape prophecies very often, or he finds loopholes, and it's hard to find a loophole in a prophecy of three words. - In the season six episode 'The Impossible Astronaut' we see a Silent vaporise a woman for, basically, gits and shiggles. She wasn't going to remember the Silent was there. This was a senseless murder, simply for the sake of it. The only thing the Silent says regards the woman is "Joy. Her name was Joy." (thank you transcripts) As Joy never gave her name, the Silents are telepathic. And seeing as Joy's name was offered up as the reason she was killed it isn't impossible to assume that Joy was killed because she was 'joy'.
- They have something that looks like a TARDIS. Other people who have a TARDIS include: the Doctor who can make or break planets at will; the Master who is stark raving mad and likes killing things; various other Time Lords who are implied to be benevolent or malevolent whenever the whim takes them. Just running off of my personal experience of people with TARDISes, chances are the Silents are bad guys.
- It is made clear over the two episodes that the Silents had imprisoned a minimum of one child (now known to be Melody/River) for a minimum of seven years against her will. In a condemned building. Driving her sole(?) human caretaker insane over Lord knows how many years. Based on the information we know now we can only see negative motives behind this. They may have been employed by Madame Kovarian. Either way, they stole Amy and Rory's baby from them for no reason. Kidnappers are bad people.
And if they did this to one family, what if they did it to others? - "Humanity should kill us on sight". They admitted it themselves. They know that what they're doing will negatively affect the human race, no matter what their overall intentions. It could be that their actions now will save someone or something else later on.
- We then find out over the course of the two-part opener that the Silents have been on Earth long enough to create a network of tunnels vast enough to startle River Song. From the Doctor's own mouth "Super parasites. Standing in the shadows of human history since the very beginning. We know they can influence human behaviour any way they want. If they've been doing that on a global scale for thousands of years..." [my emphasis].
What we get is the opinion of the protagonists.
They are working from a limited narrative viewpoint. Discounting the Melody revelation, but knowing they still abducted a child who had pictures of
Amy in her room, the TARDIS Crew know the folllowing: they've been manipulating humanity for who knows how long
and for what overall purpose, and generally? People who manipulate from the shadows are up to something sinister. Throw in the fact that the person in the space suit who shot Future!Doctor was in the same type of suit the SIlents had designed. To hold/heal/contain the girl.
Generally, people who try to kill the Doctor do so because they've done bad things.
Generally, people who mind control others also get on the Doctor's goat. Free will and such.
As far as the TARDIS Crew are concerned they were right in trying to get the Silents off of Earth. Yes, unknown numbers of Silents were killed, but their technological level (super space suits, a TARDIS-like machine, directing humanity's evolution for thousands of years) indicates they're not
stuck on Earth. And they're likely not just kept to one planet.
Besides, we know some survive because we saw a Silent in 2010 by the lake, so some survived the order given by a Silent (one they
had to obey) back in 1967.
So in-universe the kill-order was justified
as far as the protagonists were concerned, and out-of-universe the majority of people watching would agree that the Silents were a bad lot.
Besides, it's hardly as if the Doctor hasn't killed entire species before, or done worse things for no reason. Remember Harriet Jones (former Prime Minister of Great Britain)? She was meant to bring in the country's Golden Age. And the Doctor destroyed that future. Why? Because she gave the order to kill one ship of Sycorax. The Doctor had ordered the ship to leave, and they were, but the thing is, as far as
Harriet Jones was concerned, the Doctor isn't always there to save them, so she had to act in her own interests, and those of the country and the world. The Doctor may have saved that particular day, but what if the Sycorax came back? That's what she thought, and she answered: the Doctor might not be there.
Her beliefs and the Doctor's clashed, and rather than take a more moderate approach ("Don't do it again or else!") he destroyed her career, and in doing so, postponed or stopped the GOlden Age of Britain and whatever else would come from that. That being
everything that comes from it, including people, the things they did, inventions, all things based off of people's works or inventions and so on. Massive snowball.
The Doctor has also repeatedly attempted genocide on the Daleks, including once being willing to shoot the last Dalek alive (Nine in 'Dalek'). Eight/Nine also killed the Time Lords. And Ten was more than willing to just stand and watch the Racnoss die. Oh, and Four is going to genocide the Daleks before they were created.
The Doctor is more than willing to commit genocide. Odd thing to say, but that's one of the draws to the character. In this particular case, the Silents were warned, and they know that they'll die if they're seen by humans, so chances are, they're going to leave.
Only difference is that
Classic Doctors didn't tend to angst over killing them. Just another day.
Nu Doctors are all in the angst. I've heard the nicknames Ten.