WARNING: the observations made below MIGHT NOT apply to you. User experience varies on one's ISP, network setup, country, etc. See Animeraider's previous post - clearly what is one user's next best thing since sliced bread can be a steaming pile of horse manure for another.
The biggest and most annoying change for me, IMHO, is Rapidshare. Yes, I know some of you will shriek about how evil they can be because they kowtow to the demands of certain authorities and thus delete files on request, but I could nevertheless NOT deny the fact that they offered some of the fastest download speeds out there - for free. And in some cases, with little waiting time.
Well, no more. Now there's a 2m30s average waiting time to observe before being allowed to download the requested file AND if you're a free, unregistered user, the download speeds (which usually topped 900kb/s for me) are now capped at 50kb/s. So I have to bitterly bid farewell to this option - and save it as last resort.
Depositfiles...for some reason, is also getting worse. I once enjoyed decent download speeds, but today the results appear to be wildly variable. They mostly tend to loiter around an irritating <100kb/s average. On good days and depending on the file, I can still hit 100<speed<200kb/s, but it's a kind of chance-meeting I don't expect to have frequently nowadays.
Uploaded.to, the apparent popular successor to Filesonic - as far as certain overseas uploaders are concerned -...the experience varies, but half of the time I get >100kb/s or speeds comparable to Filesonic's. HOWEVER, a very annoying problem that is rising in frequency is the appearance of those "All of our free-download capacities are exhausted currently" notices.
Rapidgator is another filehost that some Japanese uploaders seem to be interested in...but up to recently it was just crap on a platter as the download button (that appears after captcha submission) usually led to a 404 or "download expired" message. It's been getting better, but in terms of QoS, it's somewhere between Uploaded.to and Depositfiles. Nothing to gawk at.
FileServe - I thought this one was diving down the drain (I was under the impression that it was going the FileSonic way - with disabled sharing), but it's still there and it still has some decent download speeds compared to the rest of the filehost landscape. In certain instances you have to wait between downloads, but in others you don't...it's kind of a coin toss, but despite that, I actually feel relieved FS is still there. I prefer it to others.
Hotfile...yeah. Still a good FH, doesn't seem to have changed much, I don't mind downloading from it at all.
Turbobit...meh. Nothing stellar, below 100kb/s.
A multi-mirror uploader that I sometimes relied on, Multiupload, seems to have gone under shortly after the MegaUpload fiasco. EmbedUpload, MirrorCreator are other services I'd turn to, but I have had a tad too many upload stalls lately to use them all the time - but that is my own experience, it might not apply to you.
Freakshare...so-so. I nevertheless rate it above Turbobit or Letitbit. More or less 100kb/s.
There is however one host that I am relatively happy with, it's WUpload. It's one of the rare hosts that seem to offer high DL speeds. I consistently hit 400kb/s speeds, but I have yet to extensively test it because it's not as popular an alternative as, say, Ul.to (uploaded.to), Turbobit, Freakshare, etc. Still, I feel quite happy when I see that this option is available.
MediaFire is what I fell back on due to sheer ease of use; it's not as fast as, say, WUpload...its new file manager page has some quirks (if an upload stalls, your next attempt to restart it will fail - unless you refresh the page, etc, etc)...but it's more than decent and there is no waiting time.