Enjoyable
My one big problem is that the shield is just too powerful, it really does make the top path worthless. I tried both. The top one has some challenge to it, but the shield on the bottom path effectively turns one life into five. If I had to change one thing, it would be to make the shield a one shot thing rather than a 4 shot thing.
Also, a couple of the bosses (the ones that fire the three lines of bullets) let you rack up lives in the most ridiculous fashion. I ended my 2nd run through with about 16 lives.
And finally, an option to disable the very repetitive D&B music while keeping the sound effects would have been nice.
Despite all that though, I did enjoy it.