Yeah, I love Monster Lair, it's the only later WB game that comes close to the original fast platformer style.
Just like the first game, Monster Lair is all about memorization, speed and getting as much fruit and other stuff (including weapons) as possible to keep your energy bar in the green and get extra men for score, so keep moving.
It's also important to know when to speed up by running on the rightmost side and to slow down to kill the baddies. If you know the level layout, you can take quick detours upwards or downwards to avoid enemies and obstacles like boulders.
The hori shmup part can be a bit tedious because not all weapons have a decent fire rate so you have to hammer on the buttons a lot (or cheat by using an auto-fire pad/stick). Here, you gotta figure out how to efficiently get rid of the bosses, there also is a small bit of luck involved what weapon powerups you'll get, some are more effective than others.
Anyway, yeah, it's a very challenging game, that's for sure, but a good one.
