Cialis (tadalafil) is powerful.. What makes Cialis unique among the erectile dysfunction drugs is its long half life. Thirty six hours after taking Cialis, a guy will still have about a quarter of what he took circulating in his blood stream. This means that guys can take this every other day and get themselves back in bad almost full time. Plus, many guys like the fact that they don't have to anticipate their love-making sessions - who can predict a woman, eh?
NOTE: Cialis has recently come out with a Cialis Daily lower dose version that can keep a guy in the game 24/7. Eli Lilly's info page is here.
However, it turns out the benefits of long term, steady use of Cialis extend way beyond just simple bedroom convenience. (For some of the scary issues with long term Cialis use, see my link on The Dangers of Cialis for more information.)
Below are listed 9 Long Term Cialis Benefits. Again, keep in mind that Cialis and other PDE5 Inhibitors affect other PDE enzyme systems, which explains the frequent stomach, vision, head and hearing issues, something you can read about in my link on Issues with PDE5 Inhibitors. I am still taking Cialis but hope to get off of it some day. However, I have gotten my dosage as low as possible: 2 mg per day.
1. Blood Flow Increases. Duh! Cialis increases blood flow - that's what erections are all about, eh? - but this can have important health benefits throughout the body as lack of circulation can effect many tissues including those in the brain. One four-week study of males (average age of 54) found that Cialis use induced profound and highly desireable cardiovascular and endothelial changes, including increases in the all-important FMD (Flow Mediated Dilation).
2. Restoration of Normal Erectile Dysfunction. One study showed that about 40% of men with E.D. were actually completely "healed" through daily Cialis use.  The dosages were fairly high however: 5 mg. I should point out, though, that we did have forum member who successfully quit it altogether, something I discuss here: How I Stopped Taking Cialis.
3. Inflammation Reduction. Researchers also noted a "robust", i.e. very significant drop in both C-Reactive Protein (CRP) and Vascular Cell Adhesion Molecule (VCAM) counts. This is important because plaque buildup in the arteries is largely due to an inflammatory process where leukocytes (white blood cells) adhere to and "attack" arterial walls.
Cialis attacks this plaque-building process in several ways, lowering both CRP, the systemic (body-wide) inflammation marker that is so intimately correlated with arterioscloerosis, and VCAM, which is a protein that helps white blood cells adhere to arterial walls and causes plaque buildup. In other words, Cialis usage seems to directly improve two important markers of cardiovascular disease. So users may get both short term benefits in the bedroom and long term health results to go with it, although that has not been proven.
4. Testeosterone and the T/E Ratio. Don't forget that long term Cialis use has been shown to significantly improve the all-important testosterone to estrogen ratio by an average of 24%. A one year study of males with an average age of 54 showed an increase in testosterone of 5.5% and a decrease in estrogen of 15%.  These are significant numbers and show the power of getting "back in the sack". Remember that the 24% increase means you have significantly more testosterone molecules floating around versus estrogen, almost always a good thing for us guys.
NOTE: Some men with erectile issues are fighting with low testosterone. If you have any doubts, get tested and check out my pages Common Causes of Low Testosterone and How to Increase Your Testosterone Naturally for more information.
5. High Blood Pressure and Hypertension. Cialis has also been shown to lower high blood pressure. Although it does not dramatically lower blood pressure, it will help most guys struggling with hypertension. [6,7,8]
6. Improved Relationships. One study found that, for guys with erectile dysfunction, a significant percentage had improved partner relationships after taking Cialis, suggesting, of course, that sex really does matter. 
7. The Benefits of Sex. In my link on How Sex Is Good For You, I document many benefits of making love. Cialis likely increases many, if not all, of these benefits. By the way, Viagra has many studies showing that it decreases the refractory period. This is the time post-ejaculation that it takes for guys to recover before they can become erect. Cialis likely has this same benefit.
8. Antidepressant Action. In some Cialis may actually act as an antidepressant.
9. Enlarged Prostate. Many urologists will give Cialis to improve enlarged prostate symptoms. In fact, it is one of the few pharmaceutical solutions that has a good track record.
So then Cialis is a no-brainer, right? Well, not so fast. All the PDE5 inhibitors have numerous side effects including possible changes of one's hearing, vision and GI tissues. I document this more extensively in my link on effects including possible changes of one's hearing, vision and GI tissues. I document this more extensively in my link on Viagra, Cialis and Levitra.
So is there a more natural solution that might have the same benefits? Well, exercise increases Nitric Oxide, just like Cialis.  Exercise lowers C-Reactive Protein long term (probably primarily due to weight loss).  Weight loss strongly lowers C-Reactive protein in numerous studies.  And weight loss, as I document in this link on the Testosterone to Estrogen Ratio, also raises testosterone while lowering estrogen significantly. (Weight training also appears to directly raise testosterone long term as well.)
In other words, one could make a strong argument that Cialis is simply a potentially dangerous substitute for exercise and weight loss. A more moderate position would be that Cialis should be used as a short term substitute until you get an exercise and weight loss program sufficiently far along.
1) International Journal of Impotence Research, 2007, 19:200 207, "Relationship between chronic tadalafil administration and improvement of endothelial function in men with erectile dysfunction: a pilot study"
2) The Journal of Sexual Medicine, Jul 2006, 3(4):716-722, "Testosterone:Estradiol Ratio Changes Associated with Long-Term Tadalafil Administration: A Pilot Study" 3) Journal of the American College of Cardiology, Dec 1996, 28(7):1652-1660, "Cardiovascular Effects of Exercise: Role of Endothelial Shear Stress"
4) J Am Coll Cardiol, 2004, 44:2411-2413, "Effect of six months' exercise training on C-reactive protein levels in healthy elderly subjects"
5) Arteriosclerosis, Thrombosis, and Vascular Biology, 2004, 24:1868, "Can Exercise Training With Weight Loss Lower Serum C-Reactive Protein Levels?"
9) International Society for Sexual Medicine, Dec 2009, 6(12):3458-3468, "Effects of 12-Month Tadalafil Therapy for Erectile Dysfunction on Couple Relationships: Results from the DETECT Study"