It's only my third day of treatment, but I wanted to echo some of the thoughts in other reviews about the initial surprise.
First, Invisalign is more noticeable than I expected. If you don't really look at my teeth, and are standing some distance away, then you wouldn't notice (unlike metal braces). However, if you do look, well the attachments are visible (kind of strange looking and jagged) lumps on my teeth and the clear tray tends to fill with saliva and have little air bubbles in it, particularly around the attachment lumps, and is visible. It generally looks like braces lite, but clearly something orthodontic is happening. Invisalign is not something to do immediately before a big event, such as a conference where you plan to present or meet many new people, a time when you are about to start dating again after a long time away, or a much anticipated vacation. Choose a time when you are ok with getting used to having something on your teeth.
Second, it does hurt. "Pressure" doesn't fully capture it. It's not that different from braces in this aspect.
Third, at the beginning they are hard to remove, and very inconvenient. Lunchtime at work is suddenly complicated. It's embarrassing to pull them out in the bathroom at work because there is a lot of saliva that trails out with the trays. On the plus side, it does help you go on a diet. Snacking is far less appealing.
Finally, the lisp is embarrassing, especially at work. You might feel the need to explain it to people as you suddenly sound like an 8 year old. You might need to take them out when you have a big meeting or phone call. They say this will get better over the first week, we'll see but I really hope so.
The number one surprise to me were the attachments. I had no idea what they would look and feel like, and had only anticipated the clear retainer like tray, which is all my orthodontist showed me. In reality, the attachments account for about 50% of the discomfort and embarrassment, and you never see them or hear much about them ahead of time.
So the message is: yes, I think it will be worth it if the projectes results are obtained, yes it is likely the best option, however it is NOT as invisible and non-invasive as they say. It's a lot more like having braces than I expected.