Switching from "first to invent" to "first to file" makes no sense to me. If you're working on something for several years and some asshat hacks your computer, copies all the data, then files the patent, why should they get credit for it?
If you can show that they did, they won't.
As to why it makes sense - the rest of the world uses a first to file system, only the US was different. This harmonizes patent law and makes it more predictable for businesses, which is a good thing. And finally, despite hundreds of posters on Slashdot telling you how big a change this was and how it guts patent law, the switch from first to invent to first to file affects about 20 patent applications per year, out of half a million filed - there were, on average, only 20 interference proceedings each year, which is where there's a dispute on who invented something first. They were horribly expensive (upwards of $30-50k) and time consuming, and they occurred only after you filed your application and went through full examination... so someone could be already out $25k getting an allowable patent and then be hit with another $50k trying to show they invented it before someone else. Instead, now you can just point to the filing date and save money.
Beyond that, I don't understand how some filers seem to be able to get patents in a few months while others take YEARS to even get reviewed. Something doesn't smell right here.
Not at all - there's a process called accelerated examination, which, for a substantial fee, pushes your application to the top of the queue. People in fast moving technologies like software tend to go for that, while people in slow moving technologies like pharmaceuticals tend to prefer waiting YEARS, since they're in FDA trials and can't actually sell any product. By allowing a fast track and slow track, everyone benefits.
And then there's the patent troll problem. Why has nobody put forth legislation that requires the patent holder to also be the applier of the technology?
Because that would make MIT, Cornell, Johns Hopkins, CalTech, etc. very, very sad and gut their research departments.