This made me think a good Bodom solo needs these elements:
It derives from the melody of the song itself and has 2-3 epic melody moments.
The rhythm and drum beat in the background is catchy.
There's a razor sharp squeal.
There's an ultra fast section and a technical section.
When it's just about playing technical, forgettable notes fast, it's boring. As in all art, the invisible foundation of everything is the emotional purpose behind everything. Many don't realize this. A song needs to come from a story/emotion, and the solo has to echo it, adding to the atmosphere, be it vicious or balladic or mysterius. When you think from the top of your mind, which solos do you remember? Everytime I Die, Follow the Reaper, Warheart, Downfall, Punch Me I Bleed, Banned from Heaven first solo... they all have emotion.