two had to be replaced because of issues. The first one lasted me about 4 years, and the second about 6.5 years, but with the help of having the mainboard replaced after about 4.5 years.
I still believe that Macs are the best hardware out there overall, but they're not without problems. I think over the last five years, some PC laptop lines have bridged the gap somewhat with Macs, and are solid machines, but generally, they still have a good ways to go. For development work, the inherent OS of the Mac is much better equipped than PCs are.
Just my .02.