Summary:
1) FP end return time is now enforced, unless the ride was closed for any part of your return window (Closure during your return window lets you use the FP any time that day). They always enforced start time, but you could use them after end time. This caused issues for rides like Splash Mountain. People would grab passes at 8am for 8:45, then not use the pass until noon when temps had warmed up. This CRUSHED the FP return and the stand-by line as suddenly 3-4x as many people were showing up with FPs than expected.
2) If you have a smart phone, get the official
Disneyland mobile app. It shows you current wait times, current FP return times of passes being handed out, full restaurant menus, let's you make restaurant reservations, shows which characters are where, etc.
3) 1-park per day ticket is now the norm for 2 day and 3 day tickets. It is a pretty hefty upgrade cost to get Hopper tickets.
4) Space Mountain now has a Star Wars overlay and is called Hyperspace Mountain.
5) Twilight Zone Tower of Terror is permanently closed and is undergoing a theme change. It will reopen (assumed summer of 2017 I believe), as Guardians of the Galaxy Mission Breakout.
6) DCA entrance plaza got a full makeover at the same time cars land was being added. Now themed to 1920s CA instead of modern day.
7) Aladdin musical has been replaced by Frozen musical.
8) Magic morning is only offered on 3-day and longer hoppers, and only if bought before showing up at the park. If you buy at the ticket booth, no mm. Only good, Tue, Thur, Sat, and only at DL. The other days are only for hotel guests and only DCA. (hotel guests can do every day, 3days of the week DL and other four days DCA. 3+day, hopper bought online can do DL days.)
9) For multi-day tickets, they snap your picture the first day. People would buy a long ticket, use only a few of the days, then sell the remaining days. People buying APs would buy partially used tickets to get the full credit of the original price against the AP cost. So, to stop people from committing fraud, they have to take your picture.
10) Radiator Springs Racers is a great ride, with a long line all day, and the FPs run out quickly. As a result, at rope drop, it is a mad dash to get RSR FPs.
11) Security now has metal detectors. Bag check, then empty the pockets into a bowl, go through metal detector, get your bags and pocket contents back. No selfie-stick policy strictly enforced. DownTown Disney is now "inside" the security parameter. Coming from Mickey and Friends, instead of park->tram->bag check, it is now park->bag check->tram. From DLR hotels, security is now by the movie theaters instead of World of
Disney Store. Guests at hotels along Disney Drive (including Paradise Pier) can no longer get into Grand CA Hotel via the front entrance. They have to go around the movie theater, through security into DTD, then can get into GCH form there. This is to prevent people from "cutting through" GCH into DTD and overwhelming he few check points there.
12) I believe that every day now, they start letting guests in half hour before posted opening time, to be held for rope drop. It used to be that on some days they would do rope drop, and other days they would hold everyone at the gates. Now it is rope drop every day. It takes me 30 minutes from entering the line for the parking garage, to pay, park, get through security, catch a tram, ride tram to DTD, walk to entrance. I like to be there half hour prior to when they start letting you in for rope drop.... That means I have to be pulling into the garage 1.5 hours prior to the posted opening (non-early entry days). It used to be that the garage opened 1 hour prior to the park, but with enhanced security it seems to be opening earlier. I have not had an issue getting into the garage 1.5 hours prior to park opening.
13) Preferred parking: Now, for $36 instead of $18, you can get front 20% corner of Mickey and Friends parking garage. Or, pay $18 and it is a crap shoot if you will be close to the escalators or 1/4 mile away at the far corner of the garage.
14) Billy Hill gone.
15) Big Thunder Trail closed for Star Wars Land consturction. Can't cut around Big Thunder to avoid Castle/Hub going between FLand and FLand.
16) Muppets gone from DCA.
Captain EO came back in place of Honey I Shrunk after MJ death, but now both are gone. Show movie previews in there when a new Star Wars movie is about to be released. Starcade (Video game arcade by Space Mt) is gone.
ummm... All I can think of off the top of my head.
Any sort of newfangled dietary magic happening these days? I'll cart in my food if I have to, I'll smuggle it in my socks if I have to. 
So, what is "early"? An hour? Two?
