Crossfit is like anything else - you get a lot of places that have shitty trainers who think "Let me throw in some gimmicky and potentially unsafe lifts from Strongman or some other training system and tell people it'll change their lives unlike any other program!" who should be strung up by their privates for jeopardizing the safety of their clients. You'll also get good, experienced coaches who know what they're doing - it's simply another case of "buyer beware" - just because someone's certified to teach something doesn't mean they're any good at it (this goes for all aspects of life, just that in training like Crossfit, it can mess you up royally in a hurry when under the guidance of an idiot). Do your research first, compare local facilities from feedback you'll get from past and current members, and of course, look for results. If a Crossfit coach has an entirely new client base every few months because people either keep getting hurt/get lackluster results/get bored with it, that's a bad sign, but if you see people who have made great transformations who keep coming back month after month, year after year, it's probably safe to assume that it's one of the better facilities you could go to. Just check out a facility thoroughly to avoid being caught in a mess of training under some dope who thinks that someone who has only touched a barbell once before should be doing heavy kettlebell complexes on their first day training.
There's nothing inherently wrong with Crossfit, but ultimately, you have to figure whether or not it is going to do what you want. Consider that the people you see on ESPN doing the Crossfit Games are NOT people who came into it as average folks, rather, you'll find that they almost all have extensive high-level athletic backgrounds in things like gymnastics, olympic lifting, etc. that gave them a great base for years prior to taking up Crossfit. Most people are going to get stronger to some degree (but, not as strong as those who simply lift for the sake of strength), will get in better overall conditioning (but not in the same ways as someone who trains for conditioning for a specific purpose, like endurance cycling), and obviously, when combined with a solid diet, it can do great improvements for one's body. But, Crossfit is a jack-of-all-trades, master-of-none type program where you're pretty much trained to be ready to be able to tackle anything within reason for overall fitness, but if you're after a specific goal of being able to, say, bench press double your bodyweight, be able to run a marathon, or anything else that's specific to a goal, it won't be ideal for someone who is after something of that nature. For the average fitness fan who is looking for something new who may have avoided weight training in the past, it's a step in the right direction, and it never hurts to improve one's conditioning, either.
I don't see Crossfit going anywhere any time soon since it started decades ago and has had a few good years entrenched as something fun and marketable, but it's definitely saturated right now, and probably won't be as large in 5 years as it is today. What'll inevitably happen is that the hucksters who are in it just to make a quick buck off something popular will fade away over the next few years, and eventually it'll be down to a pool of those who actually SHOULD be training people in Crossfit, and that's not a bad thing by any means.
"A 'hardgainer' is merely someone who hasn't bothered to try enough different training methods to learn what is actually right for their own damned body." - anonymous