This megawad has a good gameplay flow, made of many small levels, but like most single-person megawads, suffers from repetition. From halfway onwards, the levels start to look like homages to commercially-made maps. And later on, a few maps are based on missions from Star Wars: Dark Forces, and possibly from other games. The gameplay retains author's style. Overall it leans on the easy side, with too many bonuses making the job easy.
MAP05 seems broken. At some point you can't operate a lift to get back. The only escape is idclip (sorry if you're playing on nightmare).
Couldn't harm the final boss.
This wad is amazing. I had fun playing it and it had cool designed maps. In the Maps 21 - 30 is where the true challenge begins. Map 26 and Map 30 are completely hard. Map 28 is the most insane, you need to be a speedrunner to complete it or else you will be caught by It. My favourite map from this wad is Map 29 Hell on Earth. It reminds of Map 13 Downtown from Doom 2 and Map 29 Odyssey of Noises from Plutonia which I really liked both of them
In terms of pure gameplay, Skyewood is a bit of a letdown with weak geometry, small-scale encounters, and confusing map progression. In terms of pure creativity, however, Skyewood stands out even 25 years later due to its surreal visuals and originality. The forests are quite convincing for 1996 taking mouselook limitations into consideration, and the early attempts at the "void" style are quite captivating.
There are a lot of Doom maps of varying quality set inside techbases on Phobos. You won't find nearly as many that feature fire-breathing dragons, chattering trees, or exploding toads in the archives. I have to give it points for that alone.