React has one of the gentler learning curves of the front end frameworks, but it's still a lot more work than just rendering everything server-side and adding whatever minimal effects you need with jQuery.
I second sandGorgon's recommendation to use Rails. PHP is another good option. It's absolutely amazing how many successful new software companies are being built off of WordPress and/or Laravel.
I say this as someone who was using React in February 2014 and who loves to geek out over newer more powerful technologies. The thing is, your users don't care. Groupon was launched as a crappy WordPress site + a mailing list, built way past its breaking point, migrated to Rails, broke again and was a $5B company in 5 years. Many, many startups with harder-core technologists started years earlier still haven't reached where they are now even with a perpetual string of problems and failures from their IPO until now. Teespring started on Rails long after that was cool and they're a juggernaut.
Use something productive and ship it.