I own the S4 and can tell you it works great. If you don't like DeX mode then you don't have to use it in DeX mode! The resolution and colors are amazing, as is the battery life. It's fast and the S Pen is included. I bought it a few days ago from Verizon because they have a Valentine's Day special for $200 off and thought I'd upgrade from the S3. The S4 is a very good upgrade in so many ways. I've owned 2 iPad in the past so I know a bit about the iPad. I compared the S4 to the iPad Pro 11". The iPad Pro is indeed an impressive device. However the price tag is out of sight. Starts at $800 for a comparable iPad Pro 11, plus another $100 for the pen so you're at $900 plus tax plus case. That's over $1,000 ..... Yikes! I paid $550 for the S4 and another $25 for a nice case. Another plus for S4 is it accepts micro SD cards. You can add 250Gb of storage for $70 if you want. I also like the form factor on the S4 more than the iPad Pro 11. It will display Netflix, Hulu and Amazon Prime video in true wide screen form factor. The Wifi range and speed on the S4 is fantastic, as is mobile data option for Verizon.
If I had to guess I would say the iPad Pro is better for true artists. There's specific apps on the iPad Pro that are optimized for artists (there are apps for Android too but my guess is they are optimized for the iPad Pro screen size). However, the S4 may be better for overall productivity though. Office apps work flawlessly and you can plug external SSD drives directly into the USB-C port (can't do that on the iPad Pro). The S4 also charges quickly - a full charge in about 2.5 hours. DeX mode is tempting but I have not used it yet (I haven't found the need). The battery life on the S4 is a huge upgrade from the S3. The screen is also brighter than the iPad Pro 11 (although the iPad Pro 11 is plenty bright enough).
Don't give credibility to this bias review. The S4 is a great device and a bargain compared to the iPad Pro 11 if you can get it $550 as I did.