Pros
You make good friends and travel to better places then the fleet does as a Seabee. Seabees have a strong tradition of hard work and making something out of very little. Something to be proud to be a part of. Making rank to E5 is easier now then it has been in probably 10+ years. It's worth doing a contract. I enjoyed most of my time. Great benefits, pay is decent but BAH isn't keeping up with inflation at all. If you put in the work you will be rewarded most of the time. Great opportunities can come from it like working at Camp David and the state department. Being a Seabee will open doors.
Cons
Being away from family. As a Seabee assigned to sea duty expect to be away on 6 month deployments and another month or two while not deployed. They can be stuck in the past with procedures. E-6s basically delegate the majority of there work to E-5s. Being punished as a group gets old. Rank is and age are very closely tied together so if your older expect staring and dumb questions for years. Quotas to E6 in Bravo type rates is terrible like 1% which is 3 a year. Expect to take 12-15 yrs for most to make E-6 except BUs who make it quicker but have a lot more responsibility. Collaterals are over valued while members don't get enough training due funding issues.