There were three main effects I personally got from meditation:
1. A constant headache that lasted a few years and then promptly ended when I stopped meditating. Of course this could just be correlation, but it's one hell of correlation.
2. From my later experiences I found out that meditating that often and on that level (I could go into lucid REM within a minute of concentrating and then snap myself out of it at will) had a similar effect as constantly being on light doses of hallucinogenic drugs. It was really quite awesome, everything had a deep richness to it, colours were brighter, shapes were more pronounced etc.
3. Daily meditation also produced some quite interesting side-effects like being able to hold my breath for several minutes and reducing my heart rate to 40bpm (measured with an at-home cardiograph).
Another interesting effect of being able to go into REM at will was that I could live for a few years on 4 hours of daily sleep because I was in effect doing polyphasic sleep.
The only prolonged effect from meditation that I can still notice three-ish years after stopping is that I no longer dream like a normal person.
Maybe I should start meditating again, that stuff was kinda fun.