Before I found my beloved Cover Girl Lash Blast, I swore by Clinique's High Impact Mascara. It's $14.50, compared to Cover Girl's $7, and I can honestly tell you that I prefer Cover Girl now.
The problem with High Impact is that it's just kind of ... meh. It's a very wet formula, even a month after opening the tube. I find that I really have to scrape the excess off before I use it or I'll end up with globs of black on my upper lash line.
The brush is your typical nylon bristle brush, not the rubberized spiky kind that I've grown accustomed to. I found that I did have to follow up with either a lash comb or a clean rubber spiky brush to make sure I got all of my lashes separated. It's not that they "clumped" together, but the wet formula made a couple of them "stick" together, if you know what I mean.
If you can try this mascara as a gift with purchase, I'd say give it a whirl, but I wouldn't specifically run out to try it. Unless you're in the mood for a natural looking mascara that won't smear on you throughout the day.
Ah! Scary naked lashes!
One coat. Not very "high impact" if you ask me.
Looks really good from the bottom, though...