I finally got Terra Cresta II for PC Engine today; took me long enough to get hold of a decent-priced copy. Since I couldn't find a single review for it anywhere, here are my own first impressions:
Old-school enemy designs, gameplay and scoring system. Even though it was published in 1992, it has a distinct 80s-feeling to it. Difficulty is moderately high. Enemy formations are pretty standard. The backgrounds are nice looking but nothing fancy, some levels feature 2 layers. Some of the music is pretty good (you can listen to it in the sound menu).
Besides a "normal" mode Terra Cresta II also contains 2 and 5-minute Caravan modes, which is a nice addition for the score hunters among us.
You can select your ship's speed (1-4, I found "2" to be ok most of the time).
The power-up system is interesting; there are power-up capsules (numbered from 2-5 and F, the capsules must be shot open and can be used to smash enemies to their left and right) which contain parts that get added to your ship when collected.

The first one is a stronger frontal shot, then you get a rear-shot, then an even stronger frontal shot, then a rear shield.

After collecting the first power-up, you get 3 "formation marks" (F). Each time you collect an add-on, your formation marks go back to 3 (you can't hold more than 3). If you collect an (F) while you already have 3, all enemies on screen are destroyed.
If you have one or more add-ons and press "I" on your controller, one F is used up and your add-ons are positioned around your ship and become very powerful weapons for about 20 seconds (the type of power-weapon you get depends on what add-ons you have). Collecting an item and turning the formation on makes you invulnerable for a second; a life-saving feature.

The way the add-on parts are positioned and the shot-direction can be edited at the beginning of the game (reminds me of X-Out).

Some more screenshots:
Boss of level 1

Boss of level 2

Level 3

Level 4

There are several more levels; I haven't finished the game yet.
Overall Terra Cresta II is not a bad game, solid but not outstanding; maybe a 7 out of 10. Considering the price this goes for I suggest you try before you buy (due to its rarity it's one of the Engine's more expensive shmups). If you like 8bit shooters, you might enjoy it.