Definitely not. Although the Penny is easier to carry around, a Longboard is going to elevate your pushing potential and keep you cruising way faster with much less effort. Let me break it down for you...
First of all, the bigger wheels on most Longboards are 70 millimeters compared to the 59 millimeter Penny wheels and a lot of them have come way farther in wheel design and have bigger/faster cores making them way more supportive over sidewalks, bumps, rocks and chundery roads. Even with a basic core, the extra meat on there by itself increases your rollspeed a lot just by having the ability to have a bigger wheel.
Not to mention the bearings also play a big role in the wheel's performance. Longboards are going to have way better bearings on there also to help keep you rolling quick and smooth. Unlike most quality bearings on Longboards, the stock bearings on Penny's are cheaply made so they can keep the price tag low and your ride slow. The more ya know....
Also the larger size and several different designs longboards have to offer create way more stability under your feet creating more foot room, an easier push, and more confidence. That way you don't have to worry about if your foot is gonna fall off the back and turn into a spontaneous and painful yoga session.
On top of that, you got style points for days. There are several different shapes of longboards to fit whatever your preference is cruising the city. You've got drop through boards giving you that low rider feel, Pintails for a classic surfing vibe, and even Mini cruiser's that will still be easier to whip around tight spots like the Penny but with all the benefits of a longboard!