Iphone 4 still worth it? Straight Talk plan?

Hello. I am currently wondering whether I should get an iPhone 4 or not. I currently have an iPod touch 4g, and a cheap Metro PCS qwerty keyboard. I plan on buying the phone unlocked from ebay or craigslist for about $200, as AT&T's plan is too expensive for me. I also plan on using straight talk on it, so I will be paying around $45 a month. So my question is, would it be worth it? I'm not really interested in the iPhone 5 or 4S at all.

So much as you are in a good AT&T or T-Mobile coverage area, and the phone you plan on buying is a GSM model with a clean serial number, you should have no problems at all, and could be worth it.