Once I tried to play with a 4-color deck. Played for two days. I played worse than with a two-color deck. Of course you can get used to it, but I could not.
pokerstars has made a limited edition 4 colour deck that is very nice. I have seen only 1 selling on eBay for about $65. Which is too much to pay for a deck of cards but it would be a nice edition to the home game.
I love to play with the 4-color deck. It took some time to get used to, but now I could not go back to the 2-color one. Even considering buying two 4-color cardpacks from Pokerstars with my starcoins
only tried multi-color deck recently because I was multi-tabling. Sometimes my eyes plays tricks on me when I play long hours into the night and i mistake a club for a spade and vice versa.
The 4 color deck is for me absolutely mandatory to avoid mistakes when I am multitabling. I cannot remember when I played the last time with only two colors.