Depends on when OP is going. This year? Soon? Next year?
If it's soon, there is no construction at DHS. No difference at all until some more things close (only Backlot and Animation building so far) but its not yet by any means. Reading all kinds of exciting "coming in the future" plans online are one thing. Being there is another. As of Tuesday, there is definitely no noticeable change, and certainly no construction.
Great Movie Ride just had an update. It's looking quite good and fresh, animatronics looking great too. We rode it on Tuesday, had about a half hour wait in between FP windows (and RnRc was down for a few mins so couldn't Single Rider) so we popped in line. It was fine, enjoyable, nice break off your feet. It's a very popular attraction and lines can get very long, so if you see 20/30 min, I say its worth going for especially if you have never been to Hollywood Studios before.
While I personally think Fantasmic is the worst show, unlike PP, (so a lot is subjective), I can personally recommend Frozen Singalong as hilarious. Depending on when you come, there may be Frozen or Star Wars fireworks, both of which are great (and way better than Fantasmic), and a lot of new visitors have never seen Indiana Jones Stunt Show (pretty neat, don't be late to the opening as its the best part of the show). Lights Motor Action, kind of cool too, although if you see storm clouds accumulating quickly, skip it, they cancel for bad weather. Also, if Voyage of the Little Mermaid is still there, its totally worth doing. And so is Beauty and the Beast stage show. Muppets is alright.
A lot of DHS is going to consist of the live stage shows which are very entertaining if you haven't seen them in a while or are new (or just like shows).
DHS also has what I refer to as the Big Four. As mentioned above, if you like thrills, Rockin Roller Coaster is great, lines are long, but you can Single Rider if you want in most instances. If you see this line at under 30/40 min, that's a pretty low line, as its normally 60-90 or more. You will want to try and get Toy Story Mania for sure and it can usually have the longest line in the park. Fast Pass this in advance if you can, book it as early as possible. If not, you can ride it first thing at park opening (probably 40-60 min wait) or right before it closes or during Fantasmic. Tower of Terror is a light thrills super fun and lines range from 15-80, big range. If it's at a high wait time, wait until later, the line will definitely die down. You can easily Fast Pass it too. Star Tours is our other Big 4, although more insignificant than the others. It's very fun though, and if you see a high wait time, just keep an eye on it as well, as it can easily die down or you can get a FP for it. We almost always book Toy Story, Tower, Star Tours for ours FPs, unless Toy Story isn't available, then we choose RnRc instead.
If One Man's Dream is still open, go thru it as well.
Basically, you better get there quick the way the are talking lol. No real sure bet on what's staying around for how long, but if you go the way it is now, you will have plenty to do in a day , and if you are only hitting ride Highlights, than about half a day (with FPs).