Starts bad, gets a LOT better
I began watching this show as a guilty pleasure, with an emphasis on the guilt. I heard less than stellar things, but I also heard it got better. It has almost all been at least entertaining, even when it's terrible, but it becomes legitimately good in season 2 and it becomes nothing short of great past season 3. If you want to get in to the good stuff and don't like hate watching, I recommend watching the pilot (for context), the early Rogue episodes, and the two part season finale before heading into the more consistent season two.
I have mostly positive feelings about the adaptions of the characters. I really love this Cyclops. He is still uptight (accurate to the comics) but he's insanely likable and is just really nice. Jean Grey, habitually underwritten in the comics, is very well defined in this series. She has worked very hard to maintain an illusion of perfection and tries not to let people see that. It's a very interesting direction to take the character, but it works really well and is very relatable. Rogue is the best thing in the show. Making her Goth makes a lot of sense, and she is very sympathetic. Also, the chemistry between her and Scott (Cyclops) is really cute, but believable and it's no wonder the Internet is so full of fanfiction about them. Nightcrawler in this series is classic comics Nightcrawler as a kid. So many adaptions have emphasized his religiousness so much, they drowned out the rest of his personality. This is a swashbuckly, fun Nightcrawler that could grow up to star in Excalibur. Speaking of that series, this Kitty Pryde is not my Kitty Pryde. It probably wasn't smart to have her on this show, because her deal in the comics is that she is a smart teenager that's still a kid against a team of adults. In this, she begins as a painfully stereotyped valley girl. She eventually becomes fun to watch (and has a cute sibling-like relationship with Nightcrawler), but I still wonder if any franchise can possibly get her right. Professor X is more likable than usual, but he, like him in the comics, can still be a bit of a jerk. Storm is very much based on Halle Berry's performance in the movies, and that is not a complement. Evolution features a solid Wolverine. The problem with Wolverine in cartoons is that he has to be toned down for children (he is insanely brutal in the comics), and the series sidesteps this by making him a teacher (although there is an unintentionally funny moment in the pilot that where he goes into a bar and orders "Water. Cold." and leaves telling the guy to recycle the bottle). I have problems with this Magneto. He's very intimidating, but he lost the nuance from the movies and comics. The series has a good Mystique, because she shows up everywhere (if anyone is out of character, It's Probably Mystique) and while she is sympathetic, she is absolutely despicable. Also, shout-out to recurring character Boom-Boom. She isn't very well known, but she is absolutely delightful. She creates "time bombs", or little balls of energy that explode after three seconds (it's three in the comics at least). She is absolutely delightful and I watch her debut episode when I'm sick and want to just laugh and be happy. Without spoiling anything, before they reduced her to a background role, they took her in a new direction that made a lot of sense with her character and I respect that. Also, it should be noted that this series made a boring villain, Apocalypse, fascinating.
Some of these teenagers look like they're thirty (especially Jean), and I have a lot of probems with that. These teenagers aren't sexualized, which is refreshing coming from comics. The Blob character is overweight and always carries problematic messages with him. His first appearance was one of the only bad episodes that was not entertaining in the least, due to some rapey messages. These got a bit better, but that character is a lightning rod for body image issues. However, there are some great messages about diversity to be had, especially season 3 on, and all of the teenagers are likable and relatable, and many of them are solid role models. There is little to no swearing besides childish taunts and the channel was very clearly trying to avoid alcohol (see: the "water" incident). Evolution was much more aimed at kids than the other animated X-Men series, and while it affects the quality at first, it becomes fine later, and I feel less hesitation recommending it to children than Wolverine and the X-Men and the 90's animated series. This series starts too flawed to give 5 stars, but later on, it becomes a lot more complex, fun, and interesting. Highly recommended to X-Men fans.