Finally a question I can help out with! I've only been on three cruises, the most recent being Disney. My first two were Princess. The first was the Sea Princess to Alaska in May '02 and then the Star Princess to the Mexican Riviera in January '03.
The Star is a very beautiful ship - by far the most beautiful and elegant of the three. It was much more modern and visually appealing than the older Sea Princess. It was also a bit larger. It did seem to lack some of the charm the Sea Princess had but maybe it just felt that way since the Sea was our first cruise and will always hold special memories.
One thing that set Disney apart for me over either Princess cruise was the dining. I LOVED the idea of having a rotation at three restaurants that were very different. With Princess (and I imagine almost every other line), you go to the same restaurant every night. If I remember, they split people into one of two depending on if you got traditional dining or Personal Choice (just show up like you would at home).
The standard dining room we at in had a very "Lumiere's" feel to It. It was classy and we had very enjoyable meals there. There is also two pay extra (ala Palo) restaurants in addition to buffets and fast-food type places.
The food was comparable in quality to Disney. Mostly very good but a couple of things were strange. The one thing I didn't like about Disney's food was the lack of lunch options after 2pm after coming back from port. We never seemed to have that problem with Princess.
It's hard for me to compare Disney's service with Princess' as we had Personal Choice for both cruises so we had different table-mates and servers with every meal. It was nice being able to eat when we were hungry as opposed to when we were scheduled to. Also, if we didn't like our table-mates or servers (which never happened), we didn't have to worry about seeing them again.
On our
Disney cruise, we had Navneet and Constantin who we loved! We didn't realize what we were missing out on with staff who gets to know you. We travelled with friends so we still have yet to dine every night with people we just met though.
Our cabin stewards were just as good as Disney's (minus the towel animals!) but the rooms are a little smaller than Disney's.
We did notice that Disney's shows were several notches above Princess' sub-Vegas quality shows. Most were good but there were a couple cabaret shows that had me wanting to throw myself overboard to escape! But then again, after seeing Disney's shows so many times, you will probably welcome some variety!
Also, since Princess doesn't have the same family-friendly image that Disney has to uphold, the shows are a lot more adult-oriented. The adult shows on Disney were pretty clean in comparison. There is also a casino on the Princess ships with nice things such as tournaments and free classes.
Depending on where you go and for how long, there will be far fewer children than Disney but I don't know how the kids' programming is.
The Star Princess has a covered pool with a roof that opens. They kept it open most of the time in Mexico although we wish we had it in Alaska as no one used the pools for that chilly cruise!
We were obviously only repeat customers once so I don't know what all they offer as far as perks. We each received a gold-colored pin with the princess logo. We also get regular offers in the mail but the discounts don't seem any better than what we can get online.
I know they have different levels of repeat customers. At the time anyway, if it was your 2nd through 4th or 5th cruise (I don't remember), you were a Gold Member. More than that and you were a Platinum Member. I assume their website can give the specifics a lot better than I can.
I hope that helps! Maybe my DW who reads on here can add to it as she has a much better memory!
Please let me know if you have any other questions!
-steve