If you're looking to get into operating, there are a couple ways you can do it. Only you can decide if the union route is right for you. Worst case scenario is that you get into the union and you don't like it. They don't own you, you can leave at any point. Might as well try it out and see if you like it that way you'll never be asking yourself down the road "what if I would've done that". The other way is to start as a laborer for a non-union outfit and work your way into a seat, which is doable as well.
I am an operating engineer apprentice, 2nd year along and I've had my ups and downs. Got into the program last year, which was not a good year to be starting off with zero connections. Had a job that got me 6 weeks of work and was laid off. I'm now with a heavy highway crew and love it, it's tough to beat the gig I'm working at right now and I enjoy every minute I'm there.
The main reason I went union route was for the training. I've been running heavy equipment for 6 years and have only scratched the surface of what can be learned before I got into the apprenticeship program. Our training grounds are phenomenal, we have at least 5-6 pieces in various sizes of each type of equipment, that's not including the 15+ cranes we have. The instructors are the best in what they teach, there's no question about that. Whatever I feel like learning, I can do it at the grounds. Nothing will replace seat time in regards to becoming a super skilled operator, but if you want to learn the techniques of the seasoned hands, chances are there is a class that will show you how.
On top of all that, the benefits and wages are excellent. The non-union guys are starting to get close to paying what a union outfit would, but they're not quite there. As far as retirement packages go, I think I'll pass on a 401K that most companies offer after witnessing the economic crisis we've been in, it's really tough to beat a union pension.