They are strong beyond belief
1 Enchantments What Selesnya excels the most at is utilizing enchantments
Our mana rocks like Astral Cornucopia, Everflowing Chalice, Empowered Autogenerator, Mindsplice Apparatus all generate more mana as we proliferate, our storage lands like Dreadship Reef also become huge rituals, Vat of Rebirth and Lux Cannon get way more effective, we can speedrun through sagas like Phyrexian Scriptures and so much more
It takes a lot for me to get excited about another +1/+1 counters card, and Warden of the Grove wouldnt quite do it for me if it was just another riff on Master Biomancer
Two life for one card is pretty much the norm (with Card not found you are only up one card), but usually the rate is somewhat better, because theres some other benefit involved (like the scry 2)