Ow...there are many more restrictions. You need a Blackmagic DeckLink Mini Monitor 4K to have a second screen. Also in the free version of Resolve will not play some of the pro camera footage like the FS7 and FS5. I also think the free version has problems with the RED cameras.I definitely prefer Adobe Premiere Pro.
DaVinci Resolve Free has an inhibitor in that it does everything CPU render and not GPU enhanced. The "pro" version of the software will use your graphics card for rendering.
I think the price of Pro Resolve is smaller than one year of premaire .... It costed me 256,- euro Premaire wil cost 29,99 a month so x 12 = 359,88 and the next year 359,88 and the next.... Resolve Pro and al the future Resolves will free to upgrade to the next lvl as long as Blackmagic will be in business.