The portal has been great. The car rentals are actually lower in dollar amount, but I can always choose to spend UR over dollars, it's up to me. If you have some Ultimate Rewards, but not enough to pay for a ticket in full, you can use the points you have + cash. So if you decide to close the card, you can always book something with the remaining points.
The dollar cost of airline tickets is the same in the portal as with Kayak. I have been very pleased with the portal, much happier than my SPG booking portal.
I guess I am a huge Chase's portal because we have so many points in UR and Southwest with our Manufactured Spend. With Ink Bold and Ink Plus, the two of us have built well over 1.5 million points in less than 3 years.
Chase has Southwest as a customer, and we have transferred hundreds of thousands of UR points to SW. 5,000 points equates to about $100 with SW. So these 100,000 bonus points are worth a lot of flights with SW.