On the ship, as most other reviews mention, the amount of pink used is obnoxious. However, I wasn't there to be an interior design critic so you just learn to ignore is, which gets easier after a couple days. Fortunately I had a spa balcony room which is more Asian themed so I had a nice oasis from everything else.
Our cabin was absolutely wonderful, great view, mostly quiet. About the only downside was that we were in the Golden Pearl for dining, which literally meant we had to go from one corner of the ship to the other. However, the additional spa benefits were well worth it. There is tons of space for storage, including being able to stow your empty suitcases under the bed.
The spa was absolutely amazing, I really wish I had MORE time to spend in it. Although they seemed to have some problems with one of the steam rooms, they got it fixed pretty quick. Many of our days were spent rotating around the steam and dry rooms or soaking in the therapy pool.
Dining was very good. Buffet lines were almost always long but you learn real quick where all the alternate options are. My wife fell in love with the Indian food at the aft Lido. And I don't think I've ever eaten so much pizza and pastrami sandwiches. We ate in the Golden Pearl, which is the larger of the two dining rooms. The service was very good and the shows put on by the staff are worth relaxing a little after dinner to see. I felt the food was decent and had it's moments, but was never really great. The Pinnacle Steakhouse is everything they hype it up to be, and you might want to consider fasting most of the day before eating there so you will have enough room for the whole meal. Also there is another option available on a couple nights, the Chef's Table. This was one of the most amazing dining experiences I have ever enjoyed and something I wish everyone could experience. Ours started at 6:30pm and my group of 6 did not get up to leave until 11:00pm.
We didn't participate in many of the on-board activities since this was our honeymoon and we were more interested in being together, and the wonderful spa. We did enjoy the couples games and the comedians were excellent. The El Morocco Lounge was packed every night they performed. I tried the casino a couple times but it really seemed like things were tipped a little more in the House's favor than any casino in Las Vegas. We started watching a couple of the big production shows but found them to be a little cheesy, however that's just us and most people seemed to enjoy them.
We did horseback riding in Cabo San Lucas, which was fun and something my wife has always wanted to do, and on the 2nd day just wandered around a little bit. There really isn't a whole lot to see or do unless you are on an excursion or just looking to lay on the beach. I really feel Carnival needs to cut that 2nd day from Cabo and spend it in Puerto Vallarta. PV was very nice, although it was raining the day we were there, and I was glad that we had a longer day to spend there. I planned a trip for scuba diving with a third party which saved a lot of money and was a lot of fun, especially since it was just my wife, myself, and the dive-master. We also booked the Rhythms of the Night excursion which was great. Dinner was wonderful and the show was quite exciting. Plus the boat crew taking us there and back also put on quite a show. WARNING: Do not try and book this one outside of Carnival. They actually have a special showing just for the cruisers. Even then it is still down to the wire getting back to the ship, we actually had some of the crew waiting to "assist" us in making our way back to the ship.
Once we returned to Long Beach, the debarkation process was actually pretty easy. We just did the regular disembarkation and had our bags out the night before. We were able to get up at 7:30am, get ready, grab breakfast, and then just hang out for a bit until we got called. We were off the ship and walking out of the terminal shortly after 9:00am.
Overall, I feel the Carnival Splendor is an excellent value and a lot of fun, just don't expect pure luxury. There were some areas that could be improved and others that they are doing just right. The splendor may not be perfect but nothing is, and you get what you pay for. Just remember that it's you who makes your vacation fun.