You all should know my opinion.
Commander Keen is one of the greatest thing to happen to Platforming in a long long time. So much has been said about it...but I dodn't care. It's a smart, funny, great, and downright FRICKIN' CHALLENGING game series to challenge the brain. Unfortunatly, when Doom was introduced, everyone forgot about it...not that Doom is bad, but it started a trend of kids going "I'll only play violent games that have guns and weapons and stuff and not anything below T!" (Yes, there ARE people like this...).
And the GBC version wasn't AWFUL. Coul be better, yes, but it didn't suck.