I have been very pleased with FF4 so far. A few of my plug-ins no longer work but that's to be expected. It's a nice looking, quick browser that still uses more memory than I would like but I suppose that's why we all have 4GB+ of memory on our machines.
"It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring."
- Carl Sagan
Intel i7-5960X | ASUS X99-Deluxe | 16GB Crucial DDR4 | Intel 730 240GB SSD | Crucial M4 256GB SSD
WD 1TB Black x1 | 2 x ASUS Strix GTX 970 SLI | Corsair H110 Water Cooler
Corsair 750D | Windows 8.1 x64 | Dell 2410 x 3 @ 5760x1200
Intel E5-2660v1 x 2 | ASUS Z9PE-D8 WS | 128GB ECC DDR3 | WD 250GB | 24TB iSCSI Shared Storage