If you're brewing a standard ale it's a waste of time and money to use liquid yeast. Dry yeast is fine for 99% of the brewing we do.
I have found that a lot of new brewers especially, THINK they HAVE to use liquid yeast, but in reality most ales can be made with Notty, Windsor, Us-05, Us-04 and many lagers with basic Saflager.....7-8 bucks a pop for liquid as opposed to $1.50-2.50 for dry, with more cell count, is imho just a waste of money for the majority of a brewer's recipe bank...most commercial ales us a limited range of strains, and those liquid strains are really the same strains that the afore mentioned dry strains cover, for example Us-05 is the famed "Chico strain", so if you are paying 7-8 bucks for Wyeast 1056 American/Chico Ale Yeast, and you STILL have to make a starter to have enough viable cells, then you are ripping yourself off, in terms of time and money....
I use dry yeast for 99% of my beers, for basic ales I use safale 05, for more british styles I us safale 04 and for basic lagers I use saflager..
The only time I use liquid yeast is if I am making a beer where the yeast drives the style, where certain flavor characteristics are derived from the yeast, such as phenols. Like Belgian beers, where you get spicy/peppery flavors from the yeast and higher temp fermentation. Or let's say a wheat beer (needing a lowly flocculant yest) or a Kholsch, where the style of the beer uses a specific yeast strain that is un available in dry form.
But if you are looking for a "clean" yeast profile, meaning about 90% of american ales, the 05, or nottingham is the way to go. Need "Bready" or yeasty for English ales, then 04 or windsor. Want a clean, low profile lager yeast- saflager usually does the trick.
If the kit is fresh, then the yeast that comes with it will be fine.
The idea of dry yeast is "bad" is really a holdover from the bad old days of homebrew prohibition (prior to 1978 in america) when yeast came over in hot ship cargo holds, was of indeterminant pedigree and may have sat on the shelves under those cans of blue ribbon malt extract in the grocery store for god knows how long. That is simply not the case in the 21st century- all yeasts, liquid or dry ave excellent and can be used, EVEN the stuff that comes with kits.
Even John Palmer, who's book
How to brew, I really think you need to read BEFORE you try to tackle kai (consider it the Grey's anatomy of brewing books) doesn't bash dry yeast.
Palmer doesn't bash dry yeasts...
The Yeast like Notty, Us-05, u-04, and many others, made my Danstar, and fermentis are some of the best yeast around, they are just as good as the liquid strains, in fact, many are the exact same strains as those by whitelabs, and wyyeast, just in dry forms.
Good quality dry yeast has been used by commercial breweries for decades if not longer, and it was only since Homebrewing was legalized was the stuff we know available to homebrewers.
That's why every dry yeast house has industrial divisions.
Danstars website even alludes to this...
And this from Fermentis....
Beer Industrial Brewing Why use Fermentis Yeast
Bottom line, use what you want, but realize that is only a preference. Both liquid and dry are excellent these days. They both have the potential to make great or crappy beer.