Here's the quick summary.
On collusion: There was no "strong evidence" say much less anything that would rise to probable cause. At all.
On obstruction: It's complicated.
One of the reasons its complicated is intent. All criminal statutes require mens rea, with only a smattering of exceptions (oddly enough the statute Hillary violated with her "email server" does not require intent; negligence is sufficient. Nonetheless remember, she was not prosecuted.)
Obstruction is a funny statute though, in that you can obstruct an investigation into something that didn't happen. The reason for this is that the prosecution is presumed not to be corrupt!
But.... what if it is?
In this case we know it was. Specifically, we know the originating event that led to Mueller's appointment was the Steele Dossier which was a piece of opposition research paid for by a political opponent's campaign during the election and that the origin of the alleged "evidence" that gave rise to the investigation was intentionally concealed from a FISA judge and worse, it wasn't just concealed -- the FBI affirmatively lied.
Had they not lied the FISA judge would have never approved anything and there would have been no Mueller; a mere assertion alone by Ohr or Strzok without alleged facts doesn't get there. The FISA warrant on alleged verified information does. But.... the FISA warrant was predicated on repeated lies. Not mistakes -- perjury. That's a felony standing alone.
Further Mueller had no business being appointed in the first place; he was charged with investigating his own former coworkers, which is a clear conflict of interest and in violation of federal procedure governing said conflicts. In other words by the very standards of the appointing department his appointment was facially void.
To put it in simple terms the "prosecution" has been proved corrupt and worse, once that was discovered nobody stopped the investigation and indicted the corrupt individuals despite the predicate acts that gave rise to the appointment being facial felonies under long-standing Federal Law.
So this gives rise to the obvious question: Can you be convicted of obstruction if the investigation is corrupt at inception? The courts have never ruled on that as far as I know.
But I'll give you my 2 bits on how that had better be decided if it ever goes before a judge or jury:
If a court ever rules you can commit Obstruction of Justice (as a matter of a criminal law) and thus be jailed for acting to stop a corrupt investigation when same is aimed at an elected official in the United States Government then we may as well just start The Second American Revolution right here and now. A corrupt investigation or prosecution of such a person at the federal level has no check and balance; there is no further and higher law enforcement agency to appeal to. It is by definition an act of Sedition in that it seeks to overthrow a properly-elected government official through the use of force. There is no law that should ever be respected by anyone, of any political stripe, that seeks or claims to criminalize same. I give anyone using non-violent means to stop such a coup -- and that's exactly what it is -- credit for their restraint, as said restraint is by no means a part of any ethical or moral duty in such a circumstance.
We shall see if the criminally insane who knowingly cheered on and even suborned this lawless behavior by the FBI and the Left continue or fold their cards. That determination remains to be seen, but it's my bet that this report and the Democrats's reaction to it, especially by people like Cummings who is already shooting off his mouth, will do nothing more or less than drive this nation further toward a very uncivil set of events.
After all neither political party will do a damn thing about in excess of $3 trillion stolen by the medical industry from the American people every single year -- $25 per day, per person in the United States! Is it any surprise that these same people think it's perfectly fine to overthrow elections "at whim" and, by the way, what makes you think this behavior won't be repeated since there's no indication anyone has or will go to prison for any of it?