I like it. It probably took me as long to beat it that it took me to beat C&C: Renegade. However, the difference is that all I beat in HoMM4 was the first of six campaigns.
I would say, if you like those types of games, its worth it. There are a couple of anoying spots. Where you had to do one certin thing, and I skipped it somewhere along the line. It was easy enough to fix though, once you realised what you did.
Armani