Harder to roll a fat one on a CD jewel box versus a lp. There was a lot of proven research on the subject in the mid-70s. Sadly, it is a little foggy in my mind.
But seriously, CDs and MP3s work great if you are mobile, on the road commuting or airbourne as a road warrior. I am amazed I have my entire record collection fitting in a 80gig iPod which can stay with me EVERYWHERE. Newer CD players are able to dig out greater detail than before, and I expecially like the new players I hear out of the UK by Rega and Leema.
Records are great for casual listening around the home and there are some great deals on turntables. The Pro-ject 5.2 and Rega P1 and P3-24 match some of the best turntables from twenty years ago and can be had for a few hundred dollars. Quality in vinyl has never been great. Two records of the same title by artist rarely sound the same, so you have to be very careful when collecting used records. Be careful of newer releases. Reissues rarely match the original issues in master tape quality.