The job opportunities are pretty much endless right now if you have experience. There's a $50MM company moving in across the street that keeps inviting me to parties because they can't find enough people to hire. I probably get 5 e-mails from recruiters a week.

In the contracting game, there are unfortunately a large number of people who don't have a good appreciation of your costs, much more so than web dev or other types of contracting. Sifting through the haystack to find the good gigs is a royal pain.

As for the work itself, it is definitely low-level development, and when done right, it is fun & rewarding. You get different kinds of performance problems than you would get with web dev, which is fun, and the release cycles cause you to come up with some interesting solutions for tracking down and fixing issues. When you're fixing bugs in that codebase from India, on the other hand, because they wrote 20 KLOC in a single file and not a lick of memory management in the lot, you start to ponder your sanity.

Is it a good idea to get into iOS at this point? Is the marketplace crowded

Step 1) Go to Craigslist.

Step 2) Type in "ios developer" in the jobs section.

Step 3) Repeat process on variety of jobs sites/locations/keywords until curiosity satisfied.

There is lots of work available, but be prepared to fight tooth and nail to make a decent profit from it.

if you dont know Obj-C and have some js knowledge then you can get up to speed very quickly using titanium appacelerator

http://www.appcelerator.com/

Uses js to do most things, so as a stopgap until you have fully learnt Obj-C this might be a good gentle introduction to iPhone dev. It also produces Android code (with some massaging).