Yeah, though that depends on what's being crossed over.
Power Rangers Time Force X Mew Mew Power = Hell yeah! トランスフォーマー Animated X My Little ポニー = Cool 星, つ星 Trek X X-Men = Okay Lucky 星, つ星 X クモ, スパイダー Man = WTF-ville
I've written some crossovers. I wrote a Soul Eater and Black Butler one. On Quizilla, it got 4 and 5 stars. People really liked them, but I only got to chapter 6.