The first Turrican is such a frustrating, frustrating game... I hate how it's full of blind jumps! I never feel like I know where I'm going to land when I jump, unless I memorize everything which is no fun. (The TG16 version has a bunch of cut content too... I think they removed 4 of the original 16 levels from the TG16 and GB versions. Only the Genesis port had all the stages.) I love the rest of the Turrican series, but I don't like the first one all that much.
As for Universal Soldier (for Genesis), that game is a port of Turrican 2. It removed the shmup levels (and replaced them with some new platformer stages), changed the character and boss graphics, and that's it; otherwise it's a straight port of a great classic. Turrican 2 fixes almost everything wrong with the first game and then some (okay, it has the same lack of any invincibility after you get hit, but otherwise it's all better). Fantastic game. And yes, even the Genesis port is decent.
Super/Mega Turrican and beyond are fairly different from the first two games, they're much more traditional run & guns. Exceptional games, I love all three of them.